Null Reference Exception while creating bidirectional association

[MartinJSoles]

When I attempt to create a bidirectional association in VS2022 Pro (17.10.5), the designer throws a null reference exception and crashes VS.

I opened a second VS and debugged the first to capture the stack trace:

   at Sawczyn.EFDesigner.EFModel.AssociationAddRules.ElementAdded(ElementAddedEventArgs e) in D:\Code\EFDesigner2022\src\Dsl\CustomCode\Rules\AssociationAddRules.cs:line 53
   at Microsoft.VisualStudio.Modeling.AddRuleNotification.DoFireRule()
   at Microsoft.VisualStudio.Modeling.RuleNotification.FireRule()
   at Microsoft.VisualStudio.Modeling.RuleManager.FireAddRule(Transaction txn, ElementAddedEventArgs eventArgs)
   at Microsoft.VisualStudio.Modeling.RuleManager.ElementAdded(Transaction txn, AddElementLinkCommand addLinkCmd)
   at Microsoft.VisualStudio.Modeling.AddElementLinkCommand.NotifyRule()
   at Microsoft.VisualStudio.Modeling.Transaction.AddCommand(ModelCommand command)
   at Microsoft.VisualStudio.Modeling.ElementLink..ctor(Partition partition, RoleAssignment[] roleAssignments, PropertyAssignment[] propertyAssignments)
   at Sawczyn.EFDesigner.EFModel.BidirectionalAssociation..ctor(ModelClass source, ModelClass target) in D:\Code\EFDesigner2022\src\Dsl\GeneratedCode\DomainRelationships.cs:line 3889
   at Sawczyn.EFDesigner.EFModel.BidirectionalAssociationBuilder.ConnectModelClassToModelClass(ModelClass sourceAccepted, ModelClass targetAccepted) in D:\Code\EFDesigner2022\src\Dsl\CustomCode\Connection Builders\BidirectionalAssociationBuilder.cs:line 150
   at Microsoft.VisualStudio.Modeling.Diagrams.ConnectAction.CreateConnection()
   at Microsoft.VisualStudio.Modeling.Diagrams.ConnectAction.OnClicked(MouseActionEventArgs e)
   at Microsoft.VisualStudio.Modeling.Diagrams.MouseAction.InvokeStateChangeMethods(MouseActionState oldState, MouseActionState newState, DiagramClientView diagramClientView, ActionRequest nextAction)
   at Microsoft.VisualStudio.Modeling.Diagrams.MouseAction.FlushInternalEventQueue()
   at Microsoft.VisualStudio.Modeling.Diagrams.DiagramClientView.OnMouseUp(MouseEventArgs e)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at Microsoft.VisualStudio.Modeling.Diagrams.DiagramClientView.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

Oddly enough, when I added associations with the debugger attached, I was able to create a couple of associations before getting the exception thrown.