Merge pull request #33 from Natanel-Shitrit/master

Fix crash when trying to close a window when editor is empty.

Author: Hexer10

UI/MainWindowCommands.cs

@@ -114,6 +114,7 @@ private void Command_SaveAll()
         private void Command_Close()
         {
             var ee = GetCurrentEditorElement();
+            if (ee == null) return;
             DockingPane.RemoveChild(ee.Parent);
             ee.Close();
         }