# X_NOT_IMPLEMENTED_COPY_UNSCANNED

## Means

the rule found no construction of `X_NOT_IMPLEMENTED` anywhere, core's own included

## Typical cause

a scanner that read nothing answers "no copies", which is what a clean tree answers too — so core's `NotImplementedError` is the proof it read anything

## Fix

`bun test scripts/not-implemented-copies.test.ts`

[CLI and verify](/error-codes#cli-and-verify)