X_ERROR_STATUS_MISSING
Means
a framework code has no row in @ultimat3/http's closed status table
Typical cause
a package at tier 4 or below declared an X_* code and the same pull request never gave it a status, so statusFor falls to DEFAULT_STATUS (500) and packages/http/src/stages.ts reports every status >= 500 to the error monitor — a caller's typo pages the on-call. Ten codes were in that state when the rule shipped
Fix
the fix names the code — add <CODE>: <status>, to ERROR_STATUS in packages/http/src/error-map.ts, or add it to its owner's group in scripts/error-map-backlog.ts if it can never reach a request