list_allowed_values_setting_validate dies with PHP Fatal error on PHP 8.1

I am not sure if this needs a test (probably no for such an easy fix). This bug was introduced with this issue: #3025439: list_allowed_values_string() function warning when list options are determined by 'allowed_values_function' → , where the default value expression was changed.

According to the documentation, the function list_allowed_values_string() returns a string, see: https://api.drupal.org/api/drupal/modules%21field%21modules%21list%21list.module/function/list_allowed_values_string/7.x

function list_allowed_values_string
Generates a string representation of an array of 'allowed values'.

This string format is suitable for edition in a textarea.

Parameters
$values: An array of values, where array keys are values and array values are labels.

Return value
The string representation of the $values array:

Values are separated by a carriage return.
Each value is in the format "value|label" or "value".

Therefore it is correct to use an empty string instead of an empty array here. The patch seems to be correct. Thanks @dmitrii! Moving to RTBC.

Great, thank you!

Automatically closed - issue fixed for 2 weeks with no activity.