No user visible error when redis throws errors

[juliusknorr]

I observed a case where redis had a maxmemory configured and reached it. In this case

The whiteboard server logs showed:

Failed to sweep cluster state: [ErrorReply: OOM command not allowed when used memory > "maxmemory'.]
Failed to write heartbeat: [ErrorReply: OOM command not allowed when used memory > 'maxmemory'.]

However for the end user it was not noticable that there was any problem, however two users could edit the file just not see their changes.

I think this case should be catched and the frontend should not allow editing the file if no proper connection could be made.

Websocket messages that happened:

[Murazaki]

Whiteboard consumes a hecking lot of memory through redis.
I had only one whiteboard opened with images on it and it reaches 2.8GB. It is one of if not the most expensive app on my server.