WebSockets can break after computer in hibernation

[fonsp]

I've seen this a few times - when I leave Pluto running overnight, and put my computer in hibernate (i think?), the WebSocket communication is broken.

On the client side:
HTTP requests work fine. Opening a new notebook (with new UUID) still works.
The socket is openened, but no messages are received. I can send (bad) messages without closing the socket.

On the server side:
There are no errors in Pluto, not even for bad messages or closing the socket. Last night's sockets closed, and this error was thrown in Pluto.jl:457.

system: Windows 10, pluto running on Julia v1.0 in Legacy WSL Ubuntu 18

[fonsp]

This is the intended behaviour: if the client wasn't alive to process updates, the connection should be closed. (Otherwise the notebook can get out of sync while it is sleeping 😴)

[fonsp]

Yes @fonsp but what about unsaved local changes? It needs the websocket connection to save those to a file.

It should attempt to reconnect and reload all cells when this happens, but all unsaved changes should remain.

[fonsp]

#188