title: How to return customized JSON response for an error in graphene / django-graphene?
body: <p>I want to add status field to error response, so instead of this:</p>
  
  <pre><code>{
    "errors": [
      {
        "message": "Authentication credentials were not provided",
        "locations": [
          {
            "line": 2,
            "column": 3
          }
        ]
      }
    ],
    "data": {
      "viewer": null
    }
  }
  </code></pre>
  
  <p>It should be like this:</p>
  
  <pre><code>{
    "errors": [
      {
        "status": 401,  # or 400 or 403 or whatever error status suits
        "message": "Authentication credentials were not provided",
        "locations": [
          {
            "line": 2,
            "column": 3
          }
        ]
      }
    ],
    "data": {
      "viewer": null
    }
  }
  </code></pre>
  
  <p>I found out that I only can change message by raising Exception inside resolver: <code>raise Error('custom error message')</code>, but how to add field?</p>
  
  <p>Code example:</p>
  
  <pre><code>class Query(UsersQuery, graphene.ObjectType):
      me = graphene.Field(SelfUserNode)
  
      def resolve_me(self, info: ResolveInfo):
          user = info.context.user
          if not user.is_authenticated:
              # but status attr doesn't exist...
              raise GraphQLError('Authentication credentials were not provided', status=401)  
          return user
  </code></pre>