Fix "Possible EventEmitter memory leak detected. 1001 drain listeners added to [Socket]" warning. #9822

lib/mqtt.ts

@@ -69,6 +69,7 @@ export default class MQTT {
 
         return new Promise((resolve, reject) => {
             this.client = mqtt.connect(mqttSettings.server, options);
+            this.client.setMaxListeners(0);
 
             const onConnect = this.onConnect;
             this.client.on('connect', async () => {

test/stub/mqtt.js

@@ -6,6 +6,7 @@ const mock = {
     subscribe: jest.fn(),
     reconnecting: false,
     on: jest.fn(),
+    setMaxListeners: jest.fn(),
 };
 
 const mockConnect = jest.fn().mockReturnValue(mock);