function handleNotification()

in jsonrpc/src/common/connection.ts [815:881]
64 lines of code
23 McCabe index (conditional complexity)

	function handleNotification(message: NotificationMessage) {
		if (isDisposed()) {
			// See handle request.
			return;
		}
		let type: MessageSignature | undefined = undefined;
		let notificationHandler: GenericNotificationHandler | undefined;
		if (message.method === CancelNotification.type.method) {
			const cancelId = (message.params as CancelParams).id;
			knownCanceledRequests.delete(cancelId);
			traceReceivedNotification(message);
			return;
		} else {
			const element = notificationHandlers[message.method];
			if (element) {
				notificationHandler = element.handler;
				type = element.type;
			}
		}
		if (notificationHandler || starNotificationHandler) {
			try {
				traceReceivedNotification(message);
				if (notificationHandler) {
					if (message.params === undefined) {
						if (type !== undefined) {
							if (type.numberOfParams !== 0 && type.parameterStructures !== ParameterStructures.byName) {
								logger.error(`Notification ${message.method} defines ${type.numberOfParams} params but received none.`);
							}
						}
						notificationHandler();
					} else if (Array.isArray(message.params)) {
						// There are JSON-RPC libraries that send progress message as positional params although
						// specified as named. So convert them if this is the case.
						const params = message.params;
						if (message.method === ProgressNotification.type.method && params.length === 2 && ProgressToken.is(params[0])) {
							notificationHandler({ token: params[0], value: params[1] } as ProgressParams<any>);
						} else {
							if (type !== undefined) {
								if (type.parameterStructures === ParameterStructures.byName) {
									logger.error(`Notification ${message.method} defines parameters by name but received parameters by position`);
								}
								if (type.numberOfParams !== message.params.length) {
									logger.error(`Notification ${message.method} defines ${type.numberOfParams} params but received ${params.length} arguments`);
								}
							}
							notificationHandler(...params);
						}
					} else {
						if (type !== undefined && type.parameterStructures === ParameterStructures.byPosition) {
							logger.error(`Notification ${message.method} defines parameters by position but received parameters by name`);
						}
						notificationHandler(message.params);
					}
				} else if (starNotificationHandler) {
					starNotificationHandler(message.method, message.params);
				}
			} catch (error: any) {
				if (error.message) {
					logger.error(`Notification handler '${message.method}' failed with message: ${error.message}`);
				} else {
					logger.error(`Notification handler '${message.method}' failed unexpectedly.`);
				}
			}
		} else {
			unhandledNotificationEmitter.fire(message);
		}
	}