Graceful server restarts

[ojeytonwilliams]

As pointed out by @Sboonny in https://github.com/freeCodeCamp/chapter/pull/1829#pullrequestreview-1167185216 the server can be crashed by changes to the client. It's tricky to reproduce, but it does happen occasionally.

It would be nice if we could handle this in development.

Ideally, we'd want the same watch behaviour we currently have, but also to restart on errors. However it's important not to get stuck in a tight loop if the server throws an error on restart.