I tried jammr on macOS Ventura today and it crashed when joining a jam.

Is it working for anyone on Ventura?

If you have not yet upgraded to Ventura, consider waiting a little longer. I am investigating the issue now and will release a jammr update when a fix has been developed.

Good news, there is a workaround. If you experience a crash when joining a jam on macOS Ventura, try changing the sample rate in jammr's settings. The most common sample rates are 44,100 Hz and 48,000 Hz.

I'm not sure if it's specific to my soundcard (which worked fine on macOS Monterey), but the crash report shows that the error comes from the resampler in macOS. Setting the sample rate to the device's native sample rate avoids the issue.