convertEntriesOrFail
inline fun <KS : Any, VS : Any, KT : Any, VT : Any> Map<KS, VS?>.convertEntriesOrFail(path: String, keyFrom: String, keyTo: String, valueFrom: String, valueTo: String, convertKey: (KS) -> KT, convertValue: (VS) -> VT): Map<KT, VT>
Map<K, V>, OnFail.Throw: broken key/value → HARD typed MappingException at the entry path, carrying the real type pair keyFrom→keyTo or valueFrom→valueTo; null source value skips with report (absence stays type-driven); key collision → last-wins + report. CancellationException rethrows untouched.