Here is the crash dialog from Apple. Not sure what to do, it won't open at all. I was using it just fine yesterday, but now I'm locked out.
The full crash information can be found here: https://gist.github.com/nathanpalmer/4c67f4f518d3a9191f87fa6ed95f9df9
Let me know if there is anything more I can provide.
Process: Core Shell  Path: /Applications/Setapp/Core Shell.app/Contents/MacOS/Core Shell Identifier: io.coressh.shell-setapp Version: 2.0 (2755) Code Type: X86-64 (Native) Parent Process: ???  Responsible: Core Shell  User ID: 501 Date/Time: 2020-03-26 10:34:36.593 -0400 OS Version: Mac OS X 10.15.3 (19D76) Report Version: 12 Bridge OS Version: 4.2 (17P3050) Anonymous UUID: 4FAA50A5-09D7-D2C1-D76B-5A545886554D
I tried Uninstall and Reinstalling and it behaved the same. If I uninstall completely it will open up, but as soon as I enable iCloud sync it starts to do this again. Unfortunately all of my saved servers are in there (quite a lot!) so I need to get that information back.