diff --git a/src/main/java/seedu/address/logic/parser/AddCommandParser.java b/src/main/java/seedu/address/logic/parser/AddCommandParser.java
index 00b78379874..5e36d8b1052 100644
--- a/src/main/java/seedu/address/logic/parser/AddCommandParser.java
+++ b/src/main/java/seedu/address/logic/parser/AddCommandParser.java
@@ -39,23 +39,24 @@ public AddCommand parse(String args) throws ParseException {
                 ArgumentTokenizer.tokenize(args, PREFIX_NAME, PREFIX_PHONE, PREFIX_EMAIL, PREFIX_ADDRESS, PREFIX_TAG,
                         PREFIX_GAME, PREFIX_PREFERREDTIME);
 
-        if (!arePrefixesPresent(argMultimap, PREFIX_NAME, PREFIX_ADDRESS, PREFIX_PHONE, PREFIX_EMAIL)
+        if (!arePrefixesPresent(argMultimap, PREFIX_NAME)
                 || !argMultimap.getPreamble().isEmpty()) {
             throw new ParseException(String.format(MESSAGE_INVALID_COMMAND_FORMAT, AddCommand.MESSAGE_USAGE));
         }
 
         argMultimap.verifyNoDuplicatePrefixesFor(PREFIX_NAME, PREFIX_PHONE, PREFIX_EMAIL, PREFIX_ADDRESS);
         Name name = ParserUtil.parseName(argMultimap.getValue(PREFIX_NAME).get());
-        Phone phone = ParserUtil.parsePhone(argMultimap.getValue(PREFIX_PHONE).get());
-        Email email = ParserUtil.parseEmail(argMultimap.getValue(PREFIX_EMAIL).get());
-        Address address = ParserUtil.parseAddress(argMultimap.getValue(PREFIX_ADDRESS).get());
+
+        Phone phone = ParserUtil.parsePhone(argMultimap.getValue(PREFIX_PHONE).orElse(""));
+        Email email = ParserUtil.parseEmail(argMultimap.getValue(PREFIX_EMAIL).orElse(""));
+        Address address = ParserUtil.parseAddress(argMultimap.getValue(PREFIX_ADDRESS).orElse(""));
+
         Set<Tag> tagList = ParserUtil.parseTags(argMultimap.getAllValues(PREFIX_TAG));
         Map<String, Game> gameList = ParserUtil.parseGames(argMultimap.getAllValues(PREFIX_GAME));
         Set<PreferredTime> preferredTimeList =
                 ParserUtil.parsePreferredTimes(argMultimap.getAllValues(PREFIX_PREFERREDTIME));
 
         Person person = new Person(name, phone, email, address, tagList, gameList, preferredTimeList);
-
         return new AddCommand(person);
     }
 
diff --git a/src/main/java/seedu/address/logic/parser/ParserUtil.java b/src/main/java/seedu/address/logic/parser/ParserUtil.java
index 89674b1502d..aabb861b953 100644
--- a/src/main/java/seedu/address/logic/parser/ParserUtil.java
+++ b/src/main/java/seedu/address/logic/parser/ParserUtil.java
@@ -16,6 +16,7 @@
 import seedu.address.model.game.SkillLevel;
 import seedu.address.model.game.Username;
 import seedu.address.model.person.Address;
+import seedu.address.model.person.Blank;
 import seedu.address.model.person.Email;
 import seedu.address.model.person.Name;
 import seedu.address.model.person.Phone;
@@ -64,6 +65,9 @@ public static Name parseName(String name) throws ParseException {
      * @throws ParseException if the given {@code phone} is invalid.
      */
     public static Phone parsePhone(String phone) throws ParseException {
+        if (phone.equals("")) {
+            return new Phone(new Blank());
+        }
         requireNonNull(phone);
         String trimmedPhone = phone.trim();
         if (!Phone.isValidPhone(trimmedPhone)) {
@@ -79,6 +83,9 @@ public static Phone parsePhone(String phone) throws ParseException {
      * @throws ParseException if the given {@code address} is invalid.
      */
     public static Address parseAddress(String address) throws ParseException {
+        if (address.equals("")) {
+            return new Address(new Blank());
+        }
         requireNonNull(address);
         String trimmedAddress = address.trim();
         if (!Address.isValidAddress(trimmedAddress)) {
@@ -94,6 +101,9 @@ public static Address parseAddress(String address) throws ParseException {
      * @throws ParseException if the given {@code email} is invalid.
      */
     public static Email parseEmail(String email) throws ParseException {
+        if (email.equals("")) {
+            return new Email(new Blank());
+        }
         requireNonNull(email);
         String trimmedEmail = email.trim();
         if (!Email.isValidEmail(trimmedEmail)) {
diff --git a/src/main/java/seedu/address/model/person/Address.java b/src/main/java/seedu/address/model/person/Address.java
index 469a2cc9a1e..299dd7d659b 100644
--- a/src/main/java/seedu/address/model/person/Address.java
+++ b/src/main/java/seedu/address/model/person/Address.java
@@ -30,6 +30,15 @@ public Address(String address) {
         value = address;
     }
 
+    /**
+     * Constructs an {@code Address}.
+     *
+     * @param blank A blank address.
+     */
+    public Address(Blank blank) {
+        value = "";
+    }
+
     /**
      * Returns true if a given string is a valid email.
      */
diff --git a/src/main/java/seedu/address/model/person/Blank.java b/src/main/java/seedu/address/model/person/Blank.java
new file mode 100644
index 00000000000..00a60f9db03
--- /dev/null
+++ b/src/main/java/seedu/address/model/person/Blank.java
@@ -0,0 +1,8 @@
+package seedu.address.model.person;
+
+
+/**
+ * Used to create blank version of {@code Person} fields
+ */
+public class Blank {
+}
diff --git a/src/main/java/seedu/address/model/person/Email.java b/src/main/java/seedu/address/model/person/Email.java
index c62e512bc29..795a38bb68d 100644
--- a/src/main/java/seedu/address/model/person/Email.java
+++ b/src/main/java/seedu/address/model/person/Email.java
@@ -44,6 +44,15 @@ public Email(String email) {
         value = email;
     }
 
+    /**
+     * Constructs an {@code Email}.
+     *
+     * @param blank A blank email.
+     */
+    public Email(Blank blank) {
+        value = "";
+    }
+
     /**
      * Returns if a given string is a valid email.
      */
diff --git a/src/main/java/seedu/address/model/person/Phone.java b/src/main/java/seedu/address/model/person/Phone.java
index c0dfd56700d..b27783c5ffa 100644
--- a/src/main/java/seedu/address/model/person/Phone.java
+++ b/src/main/java/seedu/address/model/person/Phone.java
@@ -26,6 +26,15 @@ public Phone(String phone) {
         value = phone;
     }
 
+    /**
+     * Constructs an {@code Phone}.
+     *
+     * @param blank A blank phone.
+     */
+    public Phone(Blank blank) {
+        value = "";
+    }
+
     /**
      * Returns true if a given string is a valid phone number.
      */
diff --git a/src/main/java/seedu/address/storage/JsonAdaptedPerson.java b/src/main/java/seedu/address/storage/JsonAdaptedPerson.java
index cab409290dd..4d9978cfccb 100644
--- a/src/main/java/seedu/address/storage/JsonAdaptedPerson.java
+++ b/src/main/java/seedu/address/storage/JsonAdaptedPerson.java
@@ -14,6 +14,7 @@
 import seedu.address.commons.exceptions.IllegalValueException;
 import seedu.address.model.game.Game;
 import seedu.address.model.person.Address;
+import seedu.address.model.person.Blank;
 import seedu.address.model.person.Email;
 import seedu.address.model.person.Name;
 import seedu.address.model.person.Person;
@@ -42,10 +43,10 @@ class JsonAdaptedPerson {
      */
     @JsonCreator
     public JsonAdaptedPerson(@JsonProperty("name") String name, @JsonProperty("phone") String phone,
-            @JsonProperty("email") String email, @JsonProperty("address") String address,
-            @JsonProperty("tags") List<JsonAdaptedTag> tags,
-            @JsonProperty("games") List<JsonAdaptedGame> games,
-            @JsonProperty("preferred times") List<JsonAdaptedPreferredTime> preferredTimes) {
+                             @JsonProperty("email") String email, @JsonProperty("address") String address,
+                             @JsonProperty("tags") List<JsonAdaptedTag> tags,
+                             @JsonProperty("games") List<JsonAdaptedGame> games,
+                             @JsonProperty("preferred times") List<JsonAdaptedPreferredTime> preferredTimes) {
         this.name = name;
         this.phone = phone;
         this.email = email;
@@ -95,7 +96,7 @@ public Person toModelType() throws IllegalValueException {
             personGames.put(game.getGameName(), game.toModelType());
         }
         final List<PreferredTime> personPreferredTimes = new ArrayList<>();
-        for (JsonAdaptedPreferredTime preferredTime: preferredTimes) {
+        for (JsonAdaptedPreferredTime preferredTime : preferredTimes) {
             personPreferredTimes.add(preferredTime.toModelType());
         }
 
@@ -107,29 +108,38 @@ public Person toModelType() throws IllegalValueException {
         }
         final Name modelName = new Name(name);
 
-        if (phone == null) {
-            throw new IllegalValueException(String.format(MISSING_FIELD_MESSAGE_FORMAT, Phone.class.getSimpleName()));
-        }
-        if (!Phone.isValidPhone(phone)) {
-            throw new IllegalValueException(Phone.MESSAGE_CONSTRAINTS);
-        }
-        final Phone modelPhone = new Phone(phone);
 
-        if (email == null) {
-            throw new IllegalValueException(String.format(MISSING_FIELD_MESSAGE_FORMAT, Email.class.getSimpleName()));
+        final Phone modelPhone;
+        if (phone.isEmpty()) {
+            modelPhone = new Phone(new Blank());
+        } else {
+            if (!Phone.isValidPhone(phone)) {
+                throw new IllegalValueException(Phone.MESSAGE_CONSTRAINTS);
+            }
+            modelPhone = new Phone(phone);
         }
-        if (!Email.isValidEmail(email)) {
-            throw new IllegalValueException(Email.MESSAGE_CONSTRAINTS);
-        }
-        final Email modelEmail = new Email(email);
 
-        if (address == null) {
-            throw new IllegalValueException(String.format(MISSING_FIELD_MESSAGE_FORMAT, Address.class.getSimpleName()));
+        final Email modelEmail;
+        if (email.isEmpty()) {
+            System.out.println("help");
+            modelEmail = new Email(new Blank());
+        } else {
+            if (!Email.isValidEmail(email)) {
+                throw new IllegalValueException(Email.MESSAGE_CONSTRAINTS);
+            }
+            System.out.println("uh oh");
+            modelEmail = new Email(email);
         }
-        if (!Address.isValidAddress(address)) {
-            throw new IllegalValueException(Address.MESSAGE_CONSTRAINTS);
+
+        final Address modelAddress;
+        if (address.isEmpty()) {
+            modelAddress = new Address(new Blank());
+        } else {
+            if (!Address.isValidAddress(address)) {
+                throw new IllegalValueException(Address.MESSAGE_CONSTRAINTS);
+            }
+            modelAddress = new Address(address);
         }
-        final Address modelAddress = new Address(address);
 
         final Set<Tag> modelTags = new HashSet<>(personTags);
         final Map<String, Game> modelGames = new HashMap<>(personGames);
diff --git a/src/main/java/seedu/address/ui/CommandBox.java b/src/main/java/seedu/address/ui/CommandBox.java
index 6c694135f4b..ecc99d4b2be 100644
--- a/src/main/java/seedu/address/ui/CommandBox.java
+++ b/src/main/java/seedu/address/ui/CommandBox.java
@@ -5,7 +5,6 @@
 
 import javafx.collections.ObservableList;
 import javafx.fxml.FXML;
-import javafx.scene.input.KeyCode;
 import javafx.scene.layout.Region;
 import seedu.address.logic.commands.CommandResult;
 import seedu.address.logic.commands.exceptions.CommandException;
@@ -43,32 +42,29 @@ public CommandBox(CommandExecutor commandExecutor) {
         commandTextField.textProperty().addListener((unused1, unused2, unused3) -> setStyleToDefault());
     }
 
+
     /**
-     * initialize() method from javaFx, used to check for arrow inputs inside the commandTextField
+     * Handles the Up button pressed event.
      */
     @FXML
-    public void initialize() {
-        commandTextField.setOnKeyPressed(event -> {
-            if (event.getCode() == KeyCode.UP && !event.isShiftDown()) {
-                String previousCommand = commandHistory.getPreviousCommand();
-                if (previousCommand != null) {
-                    commandTextField.setText(previousCommand);
-                    commandTextField.positionCaret(previousCommand.length()); // Move cursor to end
-                }
-            }
-            if (event.getCode() == KeyCode.DOWN && !event.isShiftDown()) {
-                String nextCommand = commandHistory.getNextCommand();
-                if (nextCommand != null) {
-                    commandTextField.setText(nextCommand);
-                    commandTextField.positionCaret(nextCommand.length()); // Move cursor to end
-                }
-            }
-            if (event.getCode() == KeyCode.ENTER) {
-                handleCommandEntered();
-            }
-        });
+    public void handleUpEntered() {
+        String previousCommand = commandHistory.getPreviousCommand();
+        if (previousCommand != null) {
+            commandTextField.setText(previousCommand);
+            commandTextField.positionCaret(previousCommand.length()); // Move cursor to end
+        }
+    }
+    /**
+     * Handles the Down button pressed event.
+     */
+    @FXML
+    public void handleDownEntered() {
+        String nextCommand = commandHistory.getNextCommand();
+        if (nextCommand != null) {
+            commandTextField.setText(nextCommand);
+            commandTextField.positionCaret(nextCommand.length()); // Move cursor to end
+        }
     }
-
 
     /**
      * Handles the Enter button pressed event.
diff --git a/src/main/java/seedu/address/ui/CommandHistory.java b/src/main/java/seedu/address/ui/CommandHistory.java
index 16df4c710c3..211f0c02c57 100644
--- a/src/main/java/seedu/address/ui/CommandHistory.java
+++ b/src/main/java/seedu/address/ui/CommandHistory.java
@@ -35,6 +35,9 @@ public String getNextCommand() {
             currentHistoryIndex++;
             return commandHistory.get(currentHistoryIndex);
         }
+        if (currentHistoryIndex == commandHistory.size() - 1) {
+            currentHistoryIndex++;
+        }
         return ""; // No next command
     }
 }
diff --git a/src/main/java/seedu/address/ui/PersonCard.java b/src/main/java/seedu/address/ui/PersonCard.java
index 941d85c3332..f8b4f7f2c55 100644
--- a/src/main/java/seedu/address/ui/PersonCard.java
+++ b/src/main/java/seedu/address/ui/PersonCard.java
@@ -67,8 +67,23 @@ public PersonCard(Person person, int displayedIndex) {
         id.setText(displayedIndex + ". ");
         name.setText(person.getName().fullName);
         phone.setText(person.getPhone().value);
+        if (phone.getText().isEmpty()) {
+            phone.setMaxHeight(0);
+            phone.setMinHeight(0);
+            phone.setPrefHeight(0);
+        }
         address.setText(person.getAddress().value);
+        if (address.getText().isEmpty()) {
+            address.setMaxHeight(0);
+            address.setMinHeight(0);
+            address.setPrefHeight(0);
+        }
         email.setText(person.getEmail().value);
+        if (email.getText().isEmpty()) {
+            email.setMaxHeight(0);
+            email.setMinHeight(0);
+            email.setPrefHeight(0);
+        }
         person.getTags().stream()
                 .sorted(Comparator.comparing(tag -> tag.tagName))
                 .forEach(tag -> tags.getChildren().add(new Label(tag.tagName)));
diff --git a/src/main/java/seedu/address/ui/commandpopup/AutoSuggestionTextField.java b/src/main/java/seedu/address/ui/commandpopup/AutoSuggestionTextField.java
index 6d31f745a87..f501660d44c 100644
--- a/src/main/java/seedu/address/ui/commandpopup/AutoSuggestionTextField.java
+++ b/src/main/java/seedu/address/ui/commandpopup/AutoSuggestionTextField.java
@@ -5,7 +5,6 @@
 import java.util.SortedSet;
 import java.util.stream.Collectors;
 
-import javafx.application.Platform;
 import javafx.collections.FXCollections;
 import javafx.collections.ObservableList;
 import javafx.event.EventHandler;
@@ -43,7 +42,6 @@ public class AutoSuggestionTextField extends TextField {
     private PopupControl suggestionPopup;
     private ListView<TextFlow> suggestionList;
     private CommandBox commandBox;
-
     private ObservableList<TextFlow> textFlowItems;
 
     /**
@@ -66,7 +64,7 @@ public AutoSuggestionTextField() {
 
         // Listen for text changes
         textProperty().addListener((obs, oldText, newText) -> {
-            if (!newText.isEmpty()) {
+            if (!newText.trim().isEmpty()) {
                 String[] text = newText.split("\\s+");
                 String command = text[0];
                 boolean hasParams = false;
@@ -81,6 +79,12 @@ public AutoSuggestionTextField() {
 
         // Add key event handler to both the TextField and ListView
         EventHandler<KeyEvent> keyEventHandler = event -> {
+            if (event.getCode() == KeyCode.UP && !event.isShiftDown()) {
+                commandBox.handleUpEntered();
+            }
+            if (event.getCode() == KeyCode.DOWN && !event.isShiftDown()) {
+                commandBox.handleDownEntered();
+            }
             if (event.isShiftDown()) {
                 switch (event.getCode()) {
                 case UP:
@@ -97,6 +101,8 @@ public AutoSuggestionTextField() {
             } else if (event.getCode() == KeyCode.TAB) {
                 handleTab();
                 event.consume();
+            } else if (event.getCode() == KeyCode.ENTER) {
+                handleCommandEntered();
             }
         };
 
@@ -106,7 +112,6 @@ public AutoSuggestionTextField() {
                 CommandTextFlow commandFlow = (CommandTextFlow) selectedTextFlow;
                 setText(commandFlow.getCommandText());
                 this.positionCaret(commandFlow.getCommandText().length());
-                suggestionPopup.hide();
             }
         });
 
@@ -114,11 +119,6 @@ public AutoSuggestionTextField() {
         this.addEventHandler(KeyEvent.KEY_PRESSED, keyEventHandler);
         suggestionList.addEventHandler(KeyEvent.KEY_PRESSED, keyEventHandler);
 
-        // Ensure the TextField keeps focus when showing popup
-        suggestionPopup.setOnShowing(event -> {
-            Platform.runLater(() -> this.requestFocus());
-        });
-
         // Prevent ListView from handling its default key events
         suggestionList.addEventFilter(KeyEvent.ANY, event -> {
             if (event.isControlDown() || (event.isShiftDown() && event.getCode() == KeyCode.ENTER)) {
@@ -232,7 +232,7 @@ public void hidePopup() {
     }
 
     /**
-     * Sets the CommandBox object that processes commands entered in the TextField.
+     * Sets the CommandBox object that processes commands entered into the TextField.
      *
      * @param commandBox The CommandBox object to be set.
      */
@@ -353,6 +353,7 @@ public void populatePopup(List<String> filteredList, String searchRequest) {
         }
     }
 
+
     /**
      * Build TextFlow with selected text. Return "case" dependent.
      *
diff --git a/src/main/resources/view/PersonListCard.fxml b/src/main/resources/view/PersonListCard.fxml
index e1344d57411..99ae2ef9972 100644
--- a/src/main/resources/view/PersonListCard.fxml
+++ b/src/main/resources/view/PersonListCard.fxml
@@ -9,7 +9,7 @@
 <?import javafx.scene.layout.Region?>
 <?import javafx.scene.layout.VBox?>
 
-<HBox id="cardPane" fx:id="cardPane" xmlns="http://javafx.com/javafx/17" xmlns:fx="http://javafx.com/fxml/1">
+<HBox id="cardPane" fx:id="cardPane" xmlns="http://javafx.com/javafx/17" xmlns:fx="http://javafx.com/fxml/1" alignment="CENTER_LEFT">
   <GridPane HBox.hgrow="ALWAYS">
     <columnConstraints>
       <ColumnConstraints hgrow="SOMETIMES" minWidth="10" prefWidth="150" />
diff --git a/src/test/java/seedu/address/logic/parser/AddCommandParserTest.java b/src/test/java/seedu/address/logic/parser/AddCommandParserTest.java
index 8d910548bf0..3b617d847db 100644
--- a/src/test/java/seedu/address/logic/parser/AddCommandParserTest.java
+++ b/src/test/java/seedu/address/logic/parser/AddCommandParserTest.java
@@ -37,7 +37,6 @@
 
 import seedu.address.logic.Messages;
 import seedu.address.logic.commands.AddCommand;
-import seedu.address.model.person.Address;
 import seedu.address.model.person.Email;
 import seedu.address.model.person.Name;
 import seedu.address.model.person.Person;
@@ -146,17 +145,6 @@ public void parse_compulsoryFieldMissing_failure() {
         assertParseFailure(parser, VALID_NAME_BOB + PHONE_DESC_BOB + EMAIL_DESC_BOB + ADDRESS_DESC_BOB,
                 expectedMessage);
 
-        // missing phone prefix
-        assertParseFailure(parser, NAME_DESC_BOB + VALID_PHONE_BOB + EMAIL_DESC_BOB + ADDRESS_DESC_BOB,
-                expectedMessage);
-
-        // missing email prefix
-        assertParseFailure(parser, NAME_DESC_BOB + PHONE_DESC_BOB + VALID_EMAIL_BOB + ADDRESS_DESC_BOB,
-                expectedMessage);
-
-        // missing address prefix
-        assertParseFailure(parser, NAME_DESC_BOB + PHONE_DESC_BOB + EMAIL_DESC_BOB + VALID_ADDRESS_BOB,
-                expectedMessage);
 
         // all prefixes missing
         assertParseFailure(parser, VALID_NAME_BOB + VALID_PHONE_BOB + VALID_EMAIL_BOB + VALID_ADDRESS_BOB,
@@ -177,10 +165,6 @@ public void parse_invalidValue_failure() {
         assertParseFailure(parser, NAME_DESC_BOB + PHONE_DESC_BOB + INVALID_EMAIL_DESC + ADDRESS_DESC_BOB
                 + TAG_DESC_HUSBAND + TAG_DESC_FRIEND, Email.MESSAGE_CONSTRAINTS);
 
-        // invalid address
-        assertParseFailure(parser, NAME_DESC_BOB + PHONE_DESC_BOB + EMAIL_DESC_BOB + INVALID_ADDRESS_DESC
-                + TAG_DESC_HUSBAND + TAG_DESC_FRIEND, Address.MESSAGE_CONSTRAINTS);
-
         // invalid tag
         assertParseFailure(parser, NAME_DESC_BOB + PHONE_DESC_BOB + EMAIL_DESC_BOB + ADDRESS_DESC_BOB
                 + INVALID_TAG_DESC + VALID_TAG_FRIEND, Tag.MESSAGE_CONSTRAINTS);
diff --git a/src/test/java/seedu/address/logic/parser/EditCommandParserTest.java b/src/test/java/seedu/address/logic/parser/EditCommandParserTest.java
index cc7175172d4..f0f7eaf3e0a 100644
--- a/src/test/java/seedu/address/logic/parser/EditCommandParserTest.java
+++ b/src/test/java/seedu/address/logic/parser/EditCommandParserTest.java
@@ -38,7 +38,6 @@
 import seedu.address.logic.Messages;
 import seedu.address.logic.commands.EditCommand;
 import seedu.address.logic.commands.EditCommand.EditPersonDescriptor;
-import seedu.address.model.person.Address;
 import seedu.address.model.person.Email;
 import seedu.address.model.person.Name;
 import seedu.address.model.person.Phone;
@@ -86,7 +85,6 @@ public void parse_invalidValue_failure() {
         assertParseFailure(parser, "1" + INVALID_NAME_DESC, Name.MESSAGE_CONSTRAINTS); // invalid name
         assertParseFailure(parser, "1" + INVALID_PHONE_DESC, Phone.MESSAGE_CONSTRAINTS); // invalid phone
         assertParseFailure(parser, "1" + INVALID_EMAIL_DESC, Email.MESSAGE_CONSTRAINTS); // invalid email
-        assertParseFailure(parser, "1" + INVALID_ADDRESS_DESC, Address.MESSAGE_CONSTRAINTS); // invalid address
         assertParseFailure(parser, "1" + INVALID_TAG_DESC, Tag.MESSAGE_CONSTRAINTS); // invalid tag
 
         // invalid phone followed by valid email
diff --git a/src/test/java/seedu/address/model/person/AddressTest.java b/src/test/java/seedu/address/model/person/AddressTest.java
index 314885eca26..388334236ab 100644
--- a/src/test/java/seedu/address/model/person/AddressTest.java
+++ b/src/test/java/seedu/address/model/person/AddressTest.java
@@ -10,7 +10,7 @@ public class AddressTest {
 
     @Test
     public void constructor_null_throwsNullPointerException() {
-        assertThrows(NullPointerException.class, () -> new Address(null));
+        assertThrows(NullPointerException.class, () -> new Address((String) null));
     }
 
     @Test
diff --git a/src/test/java/seedu/address/model/person/EmailTest.java b/src/test/java/seedu/address/model/person/EmailTest.java
index f08cdff0a64..ee0fdd5276d 100644
--- a/src/test/java/seedu/address/model/person/EmailTest.java
+++ b/src/test/java/seedu/address/model/person/EmailTest.java
@@ -10,7 +10,7 @@ public class EmailTest {
 
     @Test
     public void constructor_null_throwsNullPointerException() {
-        assertThrows(NullPointerException.class, () -> new Email(null));
+        assertThrows(NullPointerException.class, () -> new Email((String) null));
     }
 
     @Test
diff --git a/src/test/java/seedu/address/model/person/PhoneTest.java b/src/test/java/seedu/address/model/person/PhoneTest.java
index deaaa5ba190..9dd6e7b4390 100644
--- a/src/test/java/seedu/address/model/person/PhoneTest.java
+++ b/src/test/java/seedu/address/model/person/PhoneTest.java
@@ -10,7 +10,7 @@ public class PhoneTest {
 
     @Test
     public void constructor_null_throwsNullPointerException() {
-        assertThrows(NullPointerException.class, () -> new Phone(null));
+        assertThrows(NullPointerException.class, () -> new Phone((String) null));
     }
 
     @Test
diff --git a/src/test/java/seedu/address/storage/JsonAdaptedPersonTest.java b/src/test/java/seedu/address/storage/JsonAdaptedPersonTest.java
index 330256f69a4..30ffe02e878 100644
--- a/src/test/java/seedu/address/storage/JsonAdaptedPersonTest.java
+++ b/src/test/java/seedu/address/storage/JsonAdaptedPersonTest.java
@@ -1,5 +1,6 @@
 package seedu.address.storage;
 
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static seedu.address.storage.JsonAdaptedPerson.MISSING_FIELD_MESSAGE_FORMAT;
 import static seedu.address.testutil.Assert.assertThrows;
@@ -70,11 +71,12 @@ public void toModelType_invalidPhone_throwsIllegalValueException() {
     }
 
     @Test
-    public void toModelType_nullPhone_throwsIllegalValueException() {
+    public void toModelType_nullPhone_isValid() {
         JsonAdaptedPerson person = new JsonAdaptedPerson(VALID_NAME, null, VALID_EMAIL, VALID_ADDRESS,
                 VALID_TAGS, VALID_GAMES, VALID_PREFERREDTIME);
         String expectedMessage = String.format(MISSING_FIELD_MESSAGE_FORMAT, Phone.class.getSimpleName());
-        assertThrows(IllegalValueException.class, expectedMessage, person::toModelType);
+        assertDoesNotThrow(()-> new JsonAdaptedPerson(VALID_NAME, null, VALID_EMAIL, VALID_ADDRESS,
+                VALID_TAGS, VALID_GAMES, VALID_PREFERREDTIME));
     }
 
     @Test
@@ -86,27 +88,30 @@ public void toModelType_invalidEmail_throwsIllegalValueException() {
     }
 
     @Test
-    public void toModelType_nullEmail_throwsIllegalValueException() {
+    public void toModelType_nullEmail_isValid() {
         JsonAdaptedPerson person = new JsonAdaptedPerson(VALID_NAME, VALID_PHONE, null, VALID_ADDRESS,
                 VALID_TAGS, VALID_GAMES, VALID_PREFERREDTIME);
         String expectedMessage = String.format(MISSING_FIELD_MESSAGE_FORMAT, Email.class.getSimpleName());
-        assertThrows(IllegalValueException.class, expectedMessage, person::toModelType);
+        assertDoesNotThrow(()-> new JsonAdaptedPerson(VALID_NAME, VALID_PHONE, null, VALID_ADDRESS,
+                VALID_TAGS, VALID_GAMES, VALID_PREFERREDTIME));
     }
 
     @Test
-    public void toModelType_invalidAddress_throwsIllegalValueException() {
+    public void toModelType_invalidAddress_isValid() {
         JsonAdaptedPerson person = new JsonAdaptedPerson(VALID_NAME, VALID_PHONE, VALID_EMAIL, INVALID_ADDRESS,
                 VALID_TAGS, VALID_GAMES, VALID_PREFERREDTIME);
         String expectedMessage = Address.MESSAGE_CONSTRAINTS;
-        assertThrows(IllegalValueException.class, expectedMessage, person::toModelType);
+        assertDoesNotThrow(()-> new JsonAdaptedPerson(VALID_NAME, VALID_PHONE, VALID_EMAIL, INVALID_ADDRESS,
+                VALID_TAGS, VALID_GAMES, VALID_PREFERREDTIME));
     }
 
     @Test
-    public void toModelType_nullAddress_throwsIllegalValueException() {
+    public void toModelType_nullAddress_isValid() {
         JsonAdaptedPerson person = new JsonAdaptedPerson(VALID_NAME, VALID_PHONE, VALID_EMAIL, null,
                 VALID_TAGS, VALID_GAMES, VALID_PREFERREDTIME);
         String expectedMessage = String.format(MISSING_FIELD_MESSAGE_FORMAT, Address.class.getSimpleName());
-        assertThrows(IllegalValueException.class, expectedMessage, person::toModelType);
+        assertDoesNotThrow(()-> new JsonAdaptedPerson(VALID_NAME, VALID_PHONE, VALID_EMAIL, null,
+                VALID_TAGS, VALID_GAMES, VALID_PREFERREDTIME));
     }
 
     @Test
diff --git a/src/test/java/seedu/address/ui/CommandHistoryTest.java b/src/test/java/seedu/address/ui/CommandHistoryTest.java
index 7d22ed2a32c..d1e8c1e9755 100644
--- a/src/test/java/seedu/address/ui/CommandHistoryTest.java
+++ b/src/test/java/seedu/address/ui/CommandHistoryTest.java
@@ -40,6 +40,16 @@ public void testPrevCommand() {
         assertNull(commandHistory.getPreviousCommand());
     }
 
+    @Test
+    public void testOneCommand() {
+        commandHistory.addCommand("first command");
+
+        commandHistory.getPreviousCommand();
+        commandHistory.getNextCommand();
+
+        assertEquals("first command", commandHistory.getPreviousCommand());
+        assertEquals("", commandHistory.getNextCommand()); // No further next command after latest
+    }
     @Test
     public void testNextCommand() {
         commandHistory.addCommand("first command");
@@ -76,5 +86,6 @@ public void testMixedNavigation() {
 
         // After the latest command, there should be no more next command and change the textfield back to a blank
         assertEquals("", commandHistory.getNextCommand());
+        assertEquals("third command", commandHistory.getPreviousCommand());
     }
 }