From 4dcac6193637d382358588256c55071e585ed4d5 Mon Sep 17 00:00:00 2001
From: Josh Johnson <josh@fyrelogic.com>
Date: Fri, 8 Jan 2016 21:50:30 -0500
Subject: [PATCH] Fix #15

---
 src/Extension.ts | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/Extension.ts b/src/Extension.ts
index e54d51e..379655b 100644
--- a/src/Extension.ts
+++ b/src/Extension.ts
@@ -51,6 +51,10 @@ export function deactivate() {
 }
 
 function _handleContextChange(editor: vsc.TextEditor): void {
+    if (!editor || !editor.document) {
+        return;
+    }
+    
     switch (editor.document.languageId) {
         case 'xquery':
             XQueryLintingFeatureProvider.provideXQueryDiagnostics(editor);