X_ERROR_CODE_UNDOCUMENTED
Means
a shipped error code has no row in the error reference
Typical cause
a package declared an X_* code and the same pull request never added its row
Fix
add a row for the code to wiki/Error-Codes.md — this page
a shipped error code has no row in the error reference
a package declared an X_* code and the same pull request never added its row
add a row for the code to wiki/Error-Codes.md — this page