I also have a small Swift App with a few small screens and I get the 3000 error and the API analysis file too large error.
I got past these errors with a different much bigger App a couple days ago simply by restarting xCode a few times and retrying.
I'm pretty sure the problem is on the Apple end of things because if you keep retrying it will eventually work, at least it did for me.
The secondary problem here is that "fixes" are being published that may or may not really work since it seems that the real result is based on luck. Apple seems to have created a system that works sometimes but not conssistently.
I have put a couple dozen Apps in the store over the last 6 years and my rule of thumb is now to set aside about a full day to deal with Apple problems whenever I have an updated release. Sometimes I can make a simple update in less than a day but usually is takes about a full work day. Processing the same update to the Android version takes usually one to two minutes. That's just the way it is.
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For what its' worth I finally got past this error by retrying several times and it eventually worked with no change to the App.
did Clean the Product, restart XCode and re-booted the Mac. I'm not sure if the Clean, retry or reboot made the difference because I did these several times.