Fix max listener warning from livequery server (#7083)

* fix max listner warning

* fix

* Clean test log

Author: Moumouls

spec/EnableExpressErrorHandler.spec.js

@@ -2,6 +2,7 @@ const request = require('../lib/request');
 
 describe('Enable express error handler', () => {
   it('should call the default handler in case of error, like updating a non existing object', async done => {
+    spyOn(console, 'error');
     const parseServer = await reconfigureServer(
       Object.assign({}, defaultConfiguration, {
         enableExpressErrorHandler: true,

src/Adapters/PubSub/EventEmitterPubSub.js

@@ -46,6 +46,10 @@ function createPublisher(): any {
 }
 
 function createSubscriber(): any {
+  // createSubscriber is called once at live query server start
+  // to avoid max listeners warning, we should clean up the event emitter
+  // each time this function is called
+  emitter.removeAllListeners();
   return new Subscriber(emitter);
 }