X_NOT_IMPLEMENTED_COPY

a package other than @ultimat3/core constructs X_NOT_IMPLEMENTED itself

core ships the one class (NotImplementedError); ten packages each grew a (feature, fix) wrapper of their own, with ten cause sentences for one fault, until plan 101 deleted them. A code: key, a static readonly code = and a code: held in a module const are all one finding; a registry's *_BORROWED_ERROR_CODES list names the code and raises nothing. A class that must be caught by identity extends core's (DevSourceUnavailableError)

bun run scripts/not-implemented-copies.ts --json, then in the named file throw new NotImplementedError({ cause, fix }) from @ultimat3/core — a fix: written at the call site is one the errors step reads