Fixed SD2-651: Opening a single file displays error message

git-svn-id: svn://svn.sharpdevelop.net/sharpdevelop/trunk@1030 1ccf3a8d-04fe-1044-b7c0-cef0b8235c61

src/Main/Base/Project/Src/Gui/Pads/ProjectBrowser/ProjectBrowserControl.cs

@@ -184,8 +184,11 @@ namespace ICSharpCode.SharpDevelop.Project
 		{			
 			LoggingService.DebugFormatted("Selecting Deepest for '{0}'", fileName);
 			Solution solution = ProjectService.OpenSolution;
+			if (solution == null) {
+				return;
+			}
 
-			IProject project = ProjectService.OpenSolution.FindProjectContainingFile(fileName);
+			IProject project = solution.FindProjectContainingFile(fileName);
 			if (project == null) {
 				LoggingService.Debug("no IProject found");
 				return;