Add some more null checking

Author: Krzysztof-Cieslak

src/Components/Linter.fs

@@ -63,7 +63,10 @@ module Linter =
 
 
     let private handlerOpen (event : TextEditor) =
-        parseFile event.document
+        if JS.isDefined event then
+            parseFile event.document
+        else
+            Promise.lift ()
 
     let activate (disposables: Disposable[]) =
         workspace.Globals.onDidChangeTextDocument

src/Components/QuickInfo.fs

@@ -9,29 +9,30 @@ open FunScript.TypeScript.vscode.languages
 open DTO
 open Ionide.VSCode.Helpers
 
-[<ReflectedDefinition>]
+[<ReflectedDefinition>] 
 module QuickInfo =
     let mutable private item : StatusBarItem option = None
 
     let logError (o : obj) = 
             Globals.console.warn o
 
     let private handle' (event : TextEditorSelectionChangeEvent) =
-        let doc = event.textEditor.document
-        let pos = event.selections.[0].active
-        LanguageService.tooltip (doc.fileName) (int pos.line + 1) (int pos.character + 1)
-        |> Promise.either (fun o ->
-            let res = (o.Data |> Array.fold (fun acc n -> (n |> Array.toList) @ acc ) []).Head.Signature
-            let t = res.Split('\n').[0]
-            item |> Option.iter (fun n -> n.hide ())
-            let i = window.Globals.createStatusBarItem (1 |> unbox, -1.)
-            i.text <- t
-            i.tooltip <- res
-            i.show ()
-            item <- Some i
-            ()
-        ) logError
-        |> ignore
+        if JS.isPropertyDefined event.textEditor "document" then
+            let doc = event.textEditor.document
+            let pos = event.selections.[0].active
+            LanguageService.tooltip (doc.fileName) (int pos.line + 1) (int pos.character + 1)
+            |> Promise.either (fun o ->
+                let res = (o.Data |> Array.fold (fun acc n -> (n |> Array.toList) @ acc ) []).Head.Signature
+                let t = res.Split('\n').[0]
+                item |> Option.iter (fun n -> n.hide ())
+                let i = window.Globals.createStatusBarItem (1 |> unbox, -1.)
+                i.text <- t
+                i.tooltip <- res
+                i.show ()
+                item <- Some i
+                ()
+            ) logError
+            |> ignore
 
     let mutable private timer = None : NodeJS.Timer option