Error loading existing project after dropping table in database

SkinnyPete

I've got an existing project. If I drop a table in the underlying table, even if I deselect it from the object list in the project itself, when I open the project, I get a NullReferenceException (see below).  If I add the table back, the project opens fine. I've tried dropping the table while the project is open, and then refreshing schema but the application locks up and hard closes. If I reopen it, I get the same NullReferenceException. 

Can someone help me understand how I refresh an existing project after dropping a table in the database?

************** Exception Text **************

System.NullReferenceException: Object reference not set to an instance of an object.

   at RedGate.SQLDataGenerator.Engine.Graphs.SDGTableDependencies..ctor(SDGProject sdgProject)

   at RedGate.SQLDataGenerator.Engine.Project.ErrorsAndWarnings.ErrorsAndWarningsEngine.FindDependencyErrors(SDGProject sdgProject)

   at RedGate.SQLDataGenerator.Engine.Project.ErrorsAndWarnings.ErrorsAndWarningsEngine.CalculateErrorsAndWarnings(SDGProject sdgProject)

   at RedGate.SQLDataGenerator.Engine.DataGeneratorController.CalculateErrorsAndWarningsTask()

   at RedGate.SQLDataGenerator.UI.EngineClass.CalculateWarningsAndError()

   at RedGate.SQLDataGenerator.UI.EngineClass.OpenProject(String fileName)

   at RedGate.SQLDataGenerator.UI.Controller.OpenProject(String fileName)

   at RedGate.SQLDataGenerator.UI.MainForm.DefaultStartupAction()

   at RedGate.SQLDataGenerator.UI.MainForm.MainForm_Shown(Object sender, EventArgs e)

   at System.Windows.Forms.Form.OnShown(EventArgs e)

   at System.Windows.Forms.Form.CallShownEvent()

   at System.Windows.Forms.Control.InvokeMarshaledCallbackDo(ThreadMethodEntry tme)

   at System.Windows.Forms.Control.InvokeMarshaledCallbackHelper(Object obj)

   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)

   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)

   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)

   at System.Windows.Forms.Control.InvokeMarshaledCallback(ThreadMethodEntry tme)

   at System.Windows.Forms.Control.InvokeMarshaledCallbacks()