Fix network issue (#944)

## Launch Checklist

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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

- #935

 - [x] Briefly describe the changes in this PR.
 - [x] Link to related issues.
- [x] Include before/after visuals or gifs if this PR includes visual
changes.
 - [ ] Write tests for all new functionality.
 - [x] Add an entry to `CHANGELOG.md` under the `## main` section.

CHANGELOG.md

@@ -13,6 +13,8 @@
 - _...Add new stuff here..._
 
 ### 🐞 Bug fixes
+
+- Fix incorrect handing of network error response (#944)
 - _...Add new stuff here..._
 
 ## 2.1.1

src/libs/metadata.ts

@@ -5,14 +5,17 @@ function loadJSON(url: string, defaultValue: any, cb: (...args: any[]) => void)
     mode: 'cors',
     credentials: "same-origin"
   })
-    .then(function(response) {
+    .then((response) => {
+      if (!response.ok) {
+        throw new Error('Failed to load metadata for ' + url);
+      }
       return response.json();
     })
-    .then(function(body) {
+    .then((body) => {
       cb(body)
     })
-    .catch(function() {
-      console.warn('Can not metadata for ' + url)
+    .catch(() => {
+      console.warn('Can not load metadata for ' + url + ', using default value ' + defaultValue);
       cb(defaultValue)
     })
 }