I wrote a (unsynced) widget that can crash whole games when enabled.

Maybe that is something we don't want to be possible by widgets

of course not.
but it is not really Lua script related, ie it was possible to crash games just by getting killed while FPSing a unit.

You can crash everyone else?

Yeah, it affects other people as well, makes them lag out and some people seem to get really low fps though I'm not quite sure why/how.

Just the unintended result of an experimental legitimate widget that got broken in recent versions of Spring.

I've tried it with two mods so far.

Report it and it will be fixed. We had such things in the past, too.

Pretty simple to make a private report on mantis, and thanks.