Actual Behavior

When using the single_icon_selection with the shipped Icomoon-Provider in dev environment, a warning is emmitted, which is turned into an exception and no icons are shown:

request.CRITICAL: Uncaught PHP Exception ErrorException: "Warning: Undefined array key 0" at IcomoonProvider.php line 53 {"exception":"[object] (ErrorException(code: 0): Warning: Undefined array key 0 at /var/www/html/vendor/sulu/sulu/src/Sulu/Bundle/AdminBundle/Icon/providers/IcomoonProvider.php:53)"} []

Expected Behavior

The icons should be displayed, even if the value is not correctly filled in the json-file and no warning should be thrown

Steps to Reproduce

• Add single_icon_selection with icon_set "sulu" to a template
• Open the backend
• Click on the icon selection

Possible Solutions

Replace in file src/Sulu/Bundle/AdminBundle/Icon/providers/IcomoonProvider.php::53

 - $attrs = $icon->icon->attrs[$index];
 + $attrs = $icon->icon->attrs[$index] ?? new \stdClass();