Update index.ts

packages/services/src/builder/index.ts

@@ -90,7 +90,7 @@ class BuildManager {
         throw new ServerConnection.ResponseError(response, 'Build aborted');
       }
       if (response.status !== 200) {
-        let message = 'Build failed with ${response.status}`, please run `jupyter lab build` on the server for full output';
+        let message = `Build failed with ${response.status}, please run 'jupyter lab build' on the server for full output`;
         throw new ServerConnection.ResponseError(response, message);
       }
     });