Fix error handling in worker delegation

src/worker/async_proxy.js

@@ -143,7 +143,7 @@ AsyncProxy.prototype.delegate = function(method, options) {
     }
   }
 
-  return new Promise(async (resolve, reject) => {
+  return new Promise((resolve, reject) => {
     // clone packets (for web worker structured cloning algorithm)
     this.workers[workerId].postMessage({ id:id, event:method, options:packet.clone.clonePackets(options) }, util.getTransferables(options));
     this.workers[workerId].requests++;