Variable createCoreMultiSourceEventEmitterConst

Synchronously create a network event emitter for one of the pre-approved multi-source events — those listed in MULTI_SOURCE_EVENT_NAMES. Throws synchronously if eventType is not such an event.

This is core-internal (not exposed on papiNetworkService, hence the Core in the name): multi-source events are platform events, not for extensions to create.

Unlike createNetworkEventEmitterAsync, the emitter is returned immediately so callers can use it without awaiting. Central registration with the RPC handler is performed in the background; the returned registeredEmitterPromise resolves to the same emitter once registration completes. If registration fails, the promise logs a warning and rejects with the underlying error.

Multi-source emitters are NOT unregistered on dispose (multiple emitters for the same name can coexist); the central registry cleans them up when the process disconnects. See disposeNetworkEventEmitter.