Deprecated function: mb_strlen(): Passing null to parameter #1 ($string) of type string is deprecated in drupal_strlen()

Problem/Motivation

When using PHP 8.1, if the image has no title ($image['title'] is NULL) the following error is displayed:

Deprecated function: mb_strlen(): Passing null to parameter #1 ($string) of type string is deprecated in drupal_strlen() (line 485 of /var/www/html/includes/unicode.inc).

This is because theme_cs_adaptive_image_formatter has this code:

  if (drupal_strlen($item['title']) > 0) {
    $image['title'] = $item['title'];
  }

That passes NULL to drupal_strlen(), which leads to the following:

    return mb_strlen($text);

That's where the error is thrown.

Proposed resolution

Don't call drupal_strlen() if $image['title'] is empty.

Remaining tasks

Provide a patch.

User interface changes

n/a

API changes

n/a

Data model changes

n/a