Options for the in-memory broker — the adapter behind the memory arm of
MessagingPluginOptions, constructed by it and by applications
that build InMemoryBroker directly.
onDispatchError: (error: unknown,metadata: MessageMetadata) => void | Promise<void>
Called once per REJECTED subscription handler, with the error and the
message metadata of the failed dispatch. publish resolves on dispatch
hand-off — never on handler completion — so this reporter is the terminus
of the broker's failure path: the in-memory broker has no ack model and
no redelivery to fall back on (unlike RabbitMQ, where a rejection reaching
the broker's failure path can nack and redeliver). Absent, the rejection
is still observed and settled — never an unhandled rejection — then
dropped. A reporter that itself throws or rejects is swallowed by the broker: it is
the last-resort sink, so its own failure can neither reject publish nor
abort the sibling fan-out nor surface as an unhandled rejection.
MessagingPlugin always supplies one backed by the application's logger,
so the absent case is reachable only by constructing the broker directly.