It's a bug in the partial code for step 6

[tjoskar]

It should be:

const refreshResponse = cacheResponse
    .then(response => {
        if (response) {
            // If we have cached version of the request, we should update it and inform the user
            return updatedResponse;
        }
    })
    .then(response => {
        if (response) {
            // `response` is the fetch response here
            // We should inform the user somehow here.
        }
    });
event.waitUntil(refreshResponse);

Also, take the opportunity to clarify the code.

[tjoskar]

To get step 6 to work the user must also name the api cache to api-cache-v1. try to use the global match instead.