title: Unable to infer GraphQL type from TypeScript reflection system
body: <p>I'm trying to create an Alert class as follows:</p>
  <pre><code>@ObjectType()
  export class Alert {
    @Field()
    status: 'error' | 'success' | 'warning' | 'info' | undefined
  
    @Field(() =&gt; [String])
    messages: string[];
  }
  </code></pre>
  <p>However, it gives me the following error message:</p>
  <blockquote>
  <p>Error: Unable to infer GraphQL type from TypeScript reflection system.
  You need to provide explicit type for 'status' of 'Alert' class.</p>
  </blockquote>