fix: websocket not handling 'error' event (#8)

index.js

@@ -58,6 +58,7 @@ const createServer = (aedes, options = {}) => {
       }
     }
     const ws = new WebSocket.Server({ server })
+    ws.on('error', error => server.emit('error', error))
     ws.on('connection', (conn, req) => {
       const stream = WebSocket.createWebSocketStream(conn)
       // the _socket object is needed in bindConnection to retrieve info from the stream