Duotone undefined index/array key warning

[jacobcassidy]

When using a hsl() value to create duotones in theme.json, such as:

"duotone": [
  {
    "colors": ["hsl(0, 0%, 35%)", "hsl(0, 0%, 95%)"],
    "slug": "gray-scale",
    "name": "Gray Scale"
  }
]

PHP will throw a warning about an undefined index (in PHP 7.4) or undefined array key (in PHP 8+) when a block uses that duotone on a page.

The exact warning is:
"PHP Warning: Undefined array key "" in ../wp-includes/class-wp-duotone.php on line 212"

Added an if statement with isset() to confirm that $angle_units[ $unit ] is valid before assigning it to $factor to avoid outputting a PHP warning.

[hellofromTonya]

Hello @jacobcassidy,

Welcome to WordPress Core's Trac :) Thank you for reporting this issue.

The code in question was introduced in 6.3.0 via #58555 / [56101]. Thus, I updated the Version to reflect when it was introduced.

Moving this ticket into 6.5. Adding needs-unit-tests for the patch, as PHPUnit tests can help to validate the issue and code changes and prevent future regressions.