I updated the downloads page https://www.freecadweb.org/wiki/Download
We don't have a 0.18.1 AppImage yet so that link still points to 0.17
I tested this build on osx and for me it crashed also after running tests in the gui. I have no idea why nobody has experienced crashes back then. Maybe there was a system update (on mac) which introduced these troubles with qt5.6?