Fetch API handling of response status !== 'OK'

[clhenrick]

TIL that the fetch API won't reject a Promise if the response status is not within the success range. However, it does include an ok boolean in the response which can be used to detect server side errors.

Basically the error handling should be similar to:

fetch("http://httpstat.us/500")
    .then(function(response) {
        if (!response.ok) {
            throw Error(response.statusText);
        }
        return response;
    }).then(function(response) {
        console.log("ok");
    }).catch(function(error) {
        console.log(error);
    });

See this blog post for more: https://www.tjvantoll.com/2015/09/13/fetch-and-errors/

This update applies to the Mailchimp API calls as well as the Geocode API calls.