Check for existing $metadata['sizes'] to reduce PHP warnings #632

Bug Description

As raised in the support forums users may encounter ... is undefined PHP warnings, possibly due to there not being image size arrays in the image metadata.

To lessen the likelihood of such errors check does $metadata['sizes'] in the webp-uploads/load.php file exist here, and if so exit early.

In this users example the error appeared as below:

Warning: Undefined array key “sizes” in /…/plugins/performance-lab/modules/images/webp-uploads/load.php on line 594

Warning: foreach() argument must be of type array|object, null given in /…/plugins/performance-lab/modules/images/webp-uploads/load.php on line 594

Screenshots

Additional Context

• PHP Version:
• OS: [e.g. iOS]
• Browser: [e.g. chrome, safari]
• Plugin Version: [e.g. 22]
• Device: [e.g. iPhone6]