Since patch 8.2, every time I click on guild chat or a community chat, the wow companion app would crash.
I just figured it would get fixed eventually.
Today I added a new community and I was able to go into that new community, but my old communities and real guild chat still crash the app.
In case anyone else comes across the same problem. I fixed it by completely uninstalling the app and re-installing it.
Which makes this bug probably due to a poorly written patch.
Nonetheless, the fix is in.