Fix WebSocket error

Removing .on() function because it is not a valid method and is causing
errors:
Uncaught TypeError: ws.on is not a function

The onerror event listener is already logging the error.

Signed-off-by: Yoshie Muranaka <[email protected]>
Change-Id: I6ccfa9a3a6beba93668b8c209b59560f4bf7b4bc

Author: yoshiemuranaka

src/store/plugins/WebSocketPlugin.js

@@ -28,10 +28,6 @@ const WebSocketPlugin = store => {
     ws.onopen = () => {
       ws.send(JSON.stringify(data));
     };
-    ws.on('error', function(err) {
-      console.error('error!');
-      console.error(err.code);
-    });
     ws.onerror = event => {
       console.error(event);
     };