Protect against resolve call on empty location.

Author: dgrunwald

src/AddIns/Debugger/Debugger.AddIn/Service/WindowsDebugger.cs

@@ -633,6 +633,8 @@ public override void HandleToolTipRequest(ToolTipRequestEventArgs e)
 				return;
 			if (CurrentStackFrame == null)
 				return;
+			if (e.InDocument)
+				return;
 			var resolveResult = SD.ParserService.Resolve(e.Editor, e.LogicalPosition, CurrentStackFrame.AppDomain.Compilation);
 			if (resolveResult == null)
 				return;

src/Main/SharpDevelop/Parser/ParserService.cs

@@ -278,7 +278,7 @@ public ResolveResult Resolve(ITextEditor editor, TextLocation location, ICompila
 		public ResolveResult Resolve(FileName fileName, TextLocation location, ITextSource fileContent, ICompilation compilation, CancellationToken cancellationToken)
 		{
 			var entry = GetFileEntry(fileName, true);
-			if (entry.parser == null)
+			if (entry.parser == null || location.IsEmpty)
 				return ErrorResolveResult.UnknownError;
 			IProject project = compilation != null ? compilation.GetProject() : null;
 			var parseInfo = entry.Parse(fileContent, project, cancellationToken);
@@ -334,7 +334,7 @@ public ResolveResult ResolveSnippet(FileName fileName, TextLocation fileLocation
 		public Task<ResolveResult> ResolveAsync(FileName fileName, TextLocation location, ITextSource fileContent, ICompilation compilation, CancellationToken cancellationToken)
 		{
 			var entry = GetFileEntry(fileName, true);
-			if (entry.parser == null)
+			if (entry.parser == null || location.IsEmpty)
 				return Task.FromResult<ResolveResult>(ErrorResolveResult.UnknownError);
 			IProject project = compilation != null ? compilation.GetProject() : null;
 			return entry.ParseAsync(fileContent, project, cancellationToken).ContinueWith(