Handle a 500 response with the fetch api

We have the following call to fetch.

this.http.fetch('flasher', { method: 'post', body: jsonPayload })
    .then(response => response.json())
    .then(data => console.log(data));

This works when we receive a 200 response but logs nothing to the console when we receive a 500 response. How do we handle a 500?