Fix NullReferenceException in Process.GetCurrentExecutingFrame

src/AddIns/Debugger/Debugger.AddIn/Pads/LocalVarPad.cs

@@ -66,9 +66,9 @@ namespace ICSharpCode.SharpDevelop.Gui.Pads
 			LoggingService.Info("Local Variables refresh");
 			try {
 				StackFrame frame = debuggedProcess.GetCurrentExecutingFrame();
+				localVarList.WatchItems.Clear();
 				if (frame == null) return;
 				
-				localVarList.WatchItems.Clear();
 				debuggedProcess.EnqueueForEach(
 					Dispatcher.CurrentDispatcher,
 					new StackFrameNode(frame).ChildNodes.ToList(),

src/AddIns/Debugger/Debugger.Core/Process.cs

@@ -711,6 +711,9 @@ namespace Debugger
 		
 		public StackFrame GetCurrentExecutingFrame()
 		{
+			if (IsRunning || SelectedThread == null)
+				return null;
+			
 			if (IsSelectedFrameForced()) {
 				return SelectedStackFrame; // selected from callstack or threads pads
 			}