Apply consistent-return lint rule

lib/extensions.js

@@ -65,10 +65,7 @@ function run(args, callback) {
   setTimeout(() => {
     if (id in jobs) {
       delete jobs[id];
-      return callback(null, {
-        code: "timeout",
-        message: "Extension timed out"
-      });
+      callback(null, { code: "timeout", message: "Extension timed out" });
     }
   }, TIMEOUT);