fix: instantiate constructors before using those properties

src/client/websocket/WebSocketConnection.js

@@ -44,6 +44,12 @@ class WebSocketConnection extends EventEmitter {
      */
     this.sequence = -1;
 
+    /**
+     * The current sessionID of the WebSocket
+     * @type {string}
+     */
+    this.sessionID = null;
+
     /**
      * The current status of the client
      * @type {number}