Error: Call to a member function onMessage() on null
Hi.
We found strange error in our server log:

```
Error: Call to a member function onMessage() on null
1 File "/home/api.perfops.net/vendor/cboden/ratchet/src/Ratchet/Http/HttpServer.php" line 54 in <main>
2 File "/home/api.perfops.net/vendor/cboden/ratchet/src/Ratchet/Server/IoServer.php" line 112 in onMessage
3 File "/home/api.perfops.net/vendor/cboden/ratchet/src/Ratchet/Server/IoServer.php" line 95 in onMessage
4 File "/home/api.perfops.net/vendor/evenement/evenement/src/Evenement/EventEmitterTrait.php" line 70 in handleData
5 File "/home/api.perfops.net/vendor/react/stream/src/Util.php" line 41 in Ratchet\Server\{closure}
6 File "/home/api.perfops.net/vendor/evenement/evenement/src/Evenement/EventEmitterTrait.php" line 70 in emit
7 File "/home/api.perfops.net/vendor/react/stream/src/Stream.php" line 173 in React\Stream\{closure}
8 File "<internal>" line (unknown) in emit
9 File "/home/api.perfops.net/vendor/react/event-loop/src/StreamSelectLoop.php" line 236 in handleData
10 File "/home/api.perfops.net/vendor/react/event-loop/src/StreamSelectLoop.php" line 205 in call_user_func
11 File "/home/api.perfops.net/vendor/cboden/ratchet/src/Ratchet/Server/IoServer.php" line 74 in waitForStreamActivity
12 File "/home/api.perfops.net/vendor/cboden/ratchet/src/Ratchet/App.php" line 145 in run
...
```
It looks like _httpServer was not set for some reason for connection.

Also little different but similar issue:

```
E_NOTICE: Undefined property: Ratchet\Server\IoConnection::$controller: Undefined property: Ratchet\Server\IoConnection::$controller
1 File "/home/api.perfops.net/vendor/prospect-one/yassa-rollbar/src/Yassa/Rollbar/RollbarNotifier.php" line 66 in <main>
2 File "/home/api.perfops.net/vendor/cboden/ratchet/src/Ratchet/Http/Router.php" line 71 in errorHandler
3 File "/home/api.perfops.net/vendor/cboden/ratchet/src/Ratchet/Http/HttpServer.php" line 54 in report_php_error
4 File "/home/api.perfops.net/vendor/cboden/ratchet/src/Ratchet/Server/IoServer.php" line 112 in onMessage
5 File "/home/api.perfops.net/vendor/cboden/ratchet/src/Ratchet/Server/IoServer.php" line 95 in onMessage
6 File "/home/api.perfops.net/vendor/evenement/evenement/src/Evenement/EventEmitterTrait.php" line 70 in handleData
7 File "/home/api.perfops.net/vendor/react/stream/src/Util.php" line 41 in Ratchet\Server\{closure}
8 File "/home/api.perfops.net/vendor/evenement/evenement/src/Evenement/EventEmitterTrait.php" line 70 in emit
9 File "/home/api.perfops.net/vendor/react/stream/src/Stream.php" line 173 in React\Stream\{closure}
10 File "<internal>" line (unknown) in emit
11 File "/home/api.perfops.net/vendor/react/event-loop/src/StreamSelectLoop.php" line 236 in handleData
12 File "/home/api.perfops.net/vendor/react/event-loop/src/StreamSelectLoop.php" line 205 in call_user_func
13 File "/home/api.perfops.net/vendor/cboden/ratchet/src/Ratchet/Server/IoServer.php" line 74 in waitForStreamActivity
14 File "/home/api.perfops.net/vendor/cboden/ratchet/src/Ratchet/App.php" line 145 in run
...
```

It looks like controller is empty. It catches this error then trying to send error message but _httpServer is empty as well. So it dies.
Do you have an idea what caused it and how we can make sure it won't happen again?
Thanks.