handle null GreenzoneInvalidated in tasproj recording

this previously hardcrashed the entire program when TAStudio was not open

Author: Morilli

src/BizHawk.Client.Common/movie/tasproj/TasMovie.Editing.cs

@@ -51,7 +51,7 @@ public override void Truncate(int frame)
 
 			LagLog.RemoveFrom(frame);
 			TasStateManager.InvalidateAfter(frame);
-			GreenzoneInvalidated(frame);
+			GreenzoneInvalidated?.Invoke(frame);
 			Markers.TruncateAt(frame);
 
 			ChangeLog.SetGeneralRedo();

src/BizHawk.Client.Common/movie/tasproj/TasMovie.cs

@@ -122,7 +122,7 @@ private void InvalidateAfter(int frame)
 		{
 			var anyLagInvalidated = LagLog.RemoveFrom(frame);
 			var anyStateInvalidated = TasStateManager.InvalidateAfter(frame);
-			GreenzoneInvalidated(frame);
+			GreenzoneInvalidated?.Invoke(frame);
 			if (anyLagInvalidated || anyStateInvalidated)
 			{
 				Changes = true;
@@ -286,7 +286,7 @@ public override bool ExtractInputLog(TextReader reader, out string errorMessage)
 			{
 				LagLog.RemoveFrom(timelineBranchFrame.Value);
 				TasStateManager.InvalidateAfter(timelineBranchFrame.Value);
-				GreenzoneInvalidated(timelineBranchFrame.Value);
+				GreenzoneInvalidated?.Invoke(timelineBranchFrame.Value);
 			}
 
 			return true;