NoMethodError in after callback inside Grape::Middleware::Formatter

I am getting Grape::Middleware::Formatter : undefined method `collect' for #<Stream:0x00007f685ce13270>
My code works fine, I have tested each line by my hand but if I run the whole API this error appears.
My code is as follow

        @stream = Stream.new(stream_params)
        @stream.location_id = get_location
        @stream.user_id = @streamer.id
        @stream.university = @university
        @stream.category = @category
        @stream.save!
        status(200){
          'message': 'successfully created the stream request'
        }

Start with Grape::Middleware::Formatter and reproduce the NoMethodError using the status(200) response shown in the issue. Trace the failing after callback and establish the expected response behavior; done means the reported error is reproduced, its cause is identified, and the behavior is covered by an appropriate regression test.