WebP are not created when the default editor does not support WebP

[mitogh]

Bug Description

Given 2 image editors: WP_Image_Editor_Imagick and WP_Image_Editor_GD and the default is WP_Image_Editor_Imagick if the default editor does not supports WebP but WP_Image_Editor_GD it does support WebP the tests on Site Health would return that the site supports WebP, however the current implementation does handle this case instead it uses the default image editor regardless of the support.

Support tickets:

• https://wordpress.org/support/topic/webp-image-not-created-2/
• https://wordpress.org/support/topic/webp-image-not-created/

[mitogh]

Adding a possible workaround for current users experiencing this problem:

This workaround is only supported on PHP 7.1 and above due the usage of anonymous functions.

add_filter(
	'wp_image_editors',
	function ( $editors ) {
		usort(
			$editors,
			static function( $editor ) {
				if ( call_user_func( array( $editor, 'supports_mime_type' ), 'image/webp' ) ) {
					return -1;
				}

				return 1;
			}
		);
		return $editors;
	},
	10
);

[adamsilverstein]

Related ticket where current core implementation for editor check can fail in some cases: core.trac.wordpress.org/ticket/54476 / WordPress/wordpress-develop#1918