onError property
Runs when the mutation fails for good, retries spent, after the
cache-wide MutationCache.onError, with what onMutate returned so an
optimistic update can be rolled back. A returned future is awaited; a
throw is reported to the zone and does not replace the original error.
No default.
Implementation
final OnMutationError<TVariables, TOnMutateResult>? onError;