Lwt: Lwt_main.run throws on `exit(1)`

[Schniz]

The error it says is Failure "Nested calls to Lwt_main.run are not allowed", which seems like a weird result.

I know that maybe exit(1) is not the "lwt"-ish way but maybe this error should say something else?

context: I got it as an issue in fnm: https://github.com/Schniz/fnm/issues/181
I fixed it with returning a result, instead of exiting, which is probably a better way of doing it.

[aantron]

Thanks, that was a bug in Lwt_main. The linked commit should fix it. I'll release this next Monday, mainly because there was a release this weekend, and I think I should limit the rate a little :)