Fixed expanding project node in classes pad when the project contains missing files.

src/Main/Base/Project/Src/Gui/Pads/ClassBrowser/Nodes/ProjectNode.cs

@@ -96,7 +96,7 @@ namespace ICSharpCode.SharpDevelop.Gui.ClassBrowser
 				referencesNode.AddTo(this);
 				projectContent.ReferencedContentsChanged += delegate { WorkbenchSingleton.SafeThreadAsyncCall(referencesNode.UpdateReferenceNodes); };
 				foreach (ProjectItem item in Project.GetItemsOfType(ItemType.Compile)) {
-					ParseInformation parseInformation = ParserService.GetParseInformation(item.FileName);
+					ParseInformation parseInformation = ParserService.GetExistingParseInformation(item.FileName);
 					if (parseInformation != null) {
 						InsertParseInformation(parseInformation.CompilationUnit);
 					}