Are there other VNC servers for macOS other than the built in one?
As far as I know there are no other freely available, generic VNC servers for macOS besides the built-in one and the OSXvnc program. 

There exist a commercial VNC server from TightVNC, but it is not generic in the sense that it allows VNC access to your macOS desktop - rather it is to be built in to a specific application to allow remote access to that only.

One thing you could try is a newer "fork" of OSXvnc (or rather just seem to be some guys providing updates on the seemingly otherwise abandoned OSXvnc project) here:

https://github.com/stweil/OSXvnc

There are even some pull-requests with bugfixes for a few bugs, so you might be lucky that one of those fixes your crash.