Update lib/mongoose-core.module.ts

Return MongooseError

Co-authored-by: Kamil Mysliwiec <mail@kamilmysliwiec.com>

Author: jiayisheji

lib/mongoose-core.module.ts

@@ -48,7 +48,7 @@ export class MongooseCoreModule implements OnApplicationShutdown {
       connectionFactory || ((connection) => connection);
 
     const mongooseConnectionError =
-      connectionError || ((error) => {});   
+      connectionError || ((error) => error);   
 
     const mongooseConnectionName = getConnectionToken(connectionName);