Fix network issue

[HarelM]

Launch Checklist

In case of non 200 response the font and glyphs metadata would return the ajax error object instead of the default value.

Fixes #935

• Crash - TypeError: i.map is not a function #935

• Briefly describe the changes in this PR.

• Link to related issues.

• Include before/after visuals or gifs if this PR includes visual changes.

• Write tests for all new functionality.

• Add an entry to CHANGELOG.md under the ## main section.

[pathmapper]

Thanks, confirmed this fixes the issue.

[nyurik]

LGTM.

one side question - can't we use a much more readable await syntax?

try {
  let response = await fetch(url, {
    mode: 'cors',
    credentials: "same-origin"
  });
  if (!response.ok) {
    throw new Error('Failed to load metadata for ' + url);
  }
  cb(await response.json())
}
catch (ex) {
  console.warn('Can not load metadata for ' + url + ', using default value ' + defaultValue);
  cb(defaultValue)
}

[HarelM]

We could, I didn't want to change the code a lot ,and only wanted to solve this issue. It can be done as part of a different PR...

[HarelM]

In general, this callback hell should be removed, much like we did for maplibre, but it's not a small change...