anchor.diff:                      let localParsedDocument = document.ParsedDocument
                       if localParsedDocument <> null then
                           localParsedDocument.Ast 
  -                        |> tryCast<ParseAndCheckResults>
  +                        |> Option.tryCast<ParseAndCheckResults>
                           |> Option.iter (getAndProcessSymbols >> Async.Start))
   
       let makeChunk (lineNumber: int) (style: ColorScheme) (offset:int) (extraColorInfo: (Range.range * TokenColorKind)[] option) (token: TokenInformation) =
  
positive.code:         if doc <> null && doc.Project <> null then Some doc.Project else
          let view = doc.Annotation<MonoDevelop.SourceEditor.SourceEditorView>()
          if view <> null && view.Project <> null then Some view.Project
          else IdeApp.Workspace.GetProjectsContainingFile(doc.FileName.ToString()) |> Seq.tryHead
  
      let project = getProject document
  
  
negative.code:             let extraColorInfo =
                  maybe { let! document = Option.ofNull document
                          let! parsedDocument = Option.ofNull document.ParsedDocument
                          let! pc = Option.tryCast<ParseAndCheckResults> document.ParsedDocument.Ast
                          return! pc.GetExtraColorizations() }
  
              match (this.Document, line, offset, length, style) with
  