Update extensions/ql-vscode/src/extension.ts

Co-authored-by: Aditya Sharad <6874315+adityasharad@users.noreply.github.com>

Author: mgsium

extensions/ql-vscode/src/extension.ts

@@ -501,7 +501,7 @@ async function activateWithInstalledDistribution(
     selectedQuery: Uri
   ): Promise<void> {
     // selectedQuery is unpopulated when executing through the command palette
-    const pathToQhelp =  selectedQuery ? selectedQuery.fsPath : window.activeTextEditor!.document.uri.fsPath;
+    const pathToQhelp =  selectedQuery ? selectedQuery.fsPath : window.activeTextEditor?.document.uri.fsPath;
     if(pathToQhelp) {
       // Create temporary directory
       const relativePathToMd = path.basename(pathToQhelp, '.qhelp') + '.md';