Is anyone else seeing this? I’m not running beta, but can’t see a crash on 10.15.3. I tried creating a new user account and it downloaded and launched Ok there after I OK’d the gatekeeper dialogue.
I tried using guest user account, and it failed to launch there… problem is that I think guest user account can only use apps from Mac App Store. When I manually removed quarantine attributes:
Then TaskPaper worked well from guest account also.
In your account if you go to System Preferences > Security & Privacy > General and look for the section “Allow apps downloaded from” … do you have the second option “App Store and identified developers” selected?