Add InvalidNumberError (#15)

src/errors.ts

@@ -84,6 +84,19 @@ export namespace TokenizerErrors {
             this.name = "NonFourIndentError";
         }
     }
+
+    export class InvalidNumberError extends BaseTokenizerError {
+        constructor(line: number, col: number, source: string, start: number, current: number) {
+            let msg = getFullLine(source, start) + "\n";
+            let hint = `^ Invalid Number input.`;
+            const diff = (current - start);
+            // +1 because we want the arrow to point after the string (where we expect the closing ")
+            hint = hint.padStart(hint.length + diff - MAGIC_OFFSET + 1, "~");
+            hint = hint.padStart(hint.length + col - diff, " ");
+            super(msg + hint, line, col);
+            this.name = "InvalidNumberError";
+        }
+    }
 
     export class InconsistentIndentError extends BaseTokenizerError {
         constructor(line: number, col: number, source: string, start: number) {