I also had this error yesterday and the issue was that I had put my storyboards as Development Assets and Copy Bundle Resources and they should only be in Copy Bundle Resources.
Development assets are not copied when publishing your app so I basically had no storyboards in the ipa file.
I came to this conclusion by creating a Development Distribution ipa file via Product -> Archive and then renaming that .ipa to .zip which allows you to unarchive it. Then you get an app which you can right-click and explore the contents. In it you can see what your actual app bundle looks like and check what files you have and what you're missing.
You can also install the same .ipa file to a physical iPhone/iPad device and attach a debugger to the app's process and see a lot more meaningful errors than the crash logs.
Another useful thing is to tail the logs from your physical device via Mac's Console app.
Hope this helps someone because I struggled with it for 2 days since I'm a newbie.