[Debugger] When the user clicks the Refresh button, refresh the ObjectValue

Fixes https://devdiv.visualstudio.com/DevDiv/_workitems/edit/999605/

Author: jstedfast

main/external/debugger-libs

@@ -172,7 +172,9 @@ static Task<ObjectValue[]> GetChildrenAsync (ObjectValue value, int index, int c
 
 		void OnDebuggerValueChanged (object sender, EventArgs e)
 		{
-			OnValueChanged (e);
+			Runtime.RunInMainThread (() => {
+				OnValueChanged (e);
+			}).Ignore ();
 		}
 
 		bool GetCanEdit ()

main/src/addins/MonoDevelop.Debugger/MonoDevelop.Debugger/ObjectValue/DebuggerObjectValueNode.cs

@@ -126,9 +126,9 @@ void OnPinButtonClicked (object sender, EventArgs e)
 
 		void OnLiveUpdateButtonClicked (object sender, EventArgs e)
 		{
-			if (pinned) {
+			if (Node != null && pinned) {
 				DebuggingService.SetLiveUpdateMode (TreeView.PinnedWatch, !TreeView.PinnedWatch.LiveUpdate);
-				Refresh ();
+				Node.Refresh ();
 			}
 		}