After deployment of an app to Google Play Beta I see next issue in Crashlytics (6 - 7 users are affected)
Fatal Exception: java.lang.IllegalStateException: UiAut
It seems like nothing to worry about (don't rely on accepted answer and don't remove your tests) because crashes have been reported on creating pre-launch report for google play store where some UI automation tests were executed. If you track devices on which this error has occurred - you'll see that all paths leads to pre-launch report.
You can find out more about pre-launch report here