title: NestJs websockets UnhandledPromiseRejectionWarning
body: <p>I'm trying to add a 'events' module to my application for using websockets,
  but when I add the module I get the following error:</p>
  
  <pre><code>(node:59905) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: Request mapping properties not defined in the @RequestMapping() annotation!
  (node:59905) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
  </code></pre>
  
  <p>All the other modules are loaded and mapped successfully and it only happens when I add the EventsModule</p>
  
  <p>so here's the code that I have:</p>
  
  <p>app.module.ts</p>
  
  <pre><code>@Module({
      modules: [AuthModule, DatabaseModule, UsersModule, TimespansModule, LogsModule, EntitiesModule, EventsModule]
  })
  </code></pre>
  
  <p>events.module.ts</p>
  
  <pre><code>import {EventsComponent} from './events.component';
  import {Module} from '@nestjs/common';
  @Module({
      controllers: [EventsComponent]
  })
  export class EventsModule {}
  </code></pre>
  
  <p>events.component.ts</p>
  
  <pre><code>import {WebSocketGateway, SubscribeMessage, OnGatewayConnection} from '@nestjs/websockets';
  
  @WebSocketGateway({namespace: 'events'})
  export class EventsComponent implements OnGatewayConnection {
      handleConnection(client: any) {
          console.log('client connected');
      }
  
      @SubscribeMessage('stream-received')
      onStream(client, data) {
          console.log('stream received');
      }
  }
  </code></pre>
  
  <p>I can't really see what's going wrong here, also the error message doesn't help me a lot.</p>