Follow-up to PR #9459 (merged before this fix landed). The walker
dispatcher's RPC failure paths were labeled "TRANSPORT_ERROR" and
"NIL_RESPONSE"; streaming (dispatcher/dispatcher.go) and the replay
drain (processMatches in run.go via #9462) use "RPC_ERROR" for the
same condition. Aligning so a single Prometheus query covers all
three delete paths.
Folds nil-response under RPC_ERROR rather than a separate label —
operationally it's the same class of failure (server returned no
usable response).
Chris LuandGitHub
2f682303fb