Duotone SVG function does not check for CSS variable color format

[mattf10]

The function wp_get_duotone_filter_svg and/or wp_tinycolor_string_to_rgb do not verify the format of the color code passed to it. My theme uses a CSS variable var(--nv-text-dark-bg). After getting $color from wp_tinycolor_string_to_rgb, it assumes the color array has valid values. Since the original color is not one of the expected formats, this generates the following warnings:

PHP Warning:  Trying to access array offset on value of type null in /wp-includes/block-supports/duotone.php on line 422
PHP message: PHP Warning:  Trying to access array offset on value of type null in /wp-includes/block-supports/duotone.php on line 423
PHP message: PHP Warning:  Trying to access array offset on value of type null in /wp-includes/block-supports/duotone.php on line 424
PHP message: PHP Warning:  Trying to access array offset on value of type null in /wp-includes/block-supports/duotone.php on line 425

Please change one or the other method to check for CSS variables before using values from $color array.

[sabernhardt]

Hi and thanks for the report!

I have similar warnings when I add a Cover block with duotone in the Neve theme.