Ensure we queue null

package.json

@@ -1,6 +1,6 @@
 {
   "name": "vscode-nls-dev",
-  "version": "3.0.6",
+  "version": "3.0.7",
   "description": "Development time npm module to generate strings bundles from Javascript files",
   "author": "Microsoft Corporation",
   "license": "MIT",

src/main.ts

@@ -618,6 +618,7 @@ export function createXlfFiles(projectName: string, extensionName: string): Thro
 			});
 			this.queue(xlfFile);
 		}
+		this.queue(null);
 	});
 }