Swagger: TypeError: Failed to get

Question

I am trying to define a simple API that pretty much relates to health checks. My problem is that the requests are correct, the answer I get from the server is correct, but it is not displayed using swagger: http://imgur.com/a/pgTL4

Here's the answer I get (which is correct): http://imgur.com/a/qPLZy and HTTP status 200: http://imgur.com/a/LmIpf

In addition, I determined the HTTP status of 200 and 500: http://imgur.com/a/eaxfr

Does anyone have a hint? Thank.