pthumb.class.php not compliant with php < 8.x (use 'mixed' type in member function)

[intersel]

Bug report

Summary

When looking at images in the media browser in the manager using php version < 8 (like 7.4.3), it generates the following error:

PHP Fatal error: Uncaught TypeError: Argument 2 passed to phpthumb::__set() must be an instance of mixed, bool given in xxxx/core/model/phpthumb/phpthumb.class.php

Step to reproduce

open media browser and got to a directory where you have an image

Observed behavior

PHP Fatal error: Uncaught TypeError: Argument 2 passed to phpthumb::__set() must be an instance of mixed, bool given

Expected behavior

no php error... as server requirements on the modx website are about php:
Component Minimum Required Recommended for Production
PHP 5.6.x 7.4+

To solve the problem, it is needed to change line 317 in core/model/phpthumb/phpthumb.class.php

//public function __set(string $name, mixed $value): void {
public function __set(string $name, $value): void {
}

Environment

MODX version, apache/nginx and version, mysql version, browser, etc. Any relevant information.
Modx V2.8.6, Apache/2.4.38 (Debian) PHP 7.4.33

[halftrainedharry]

Duplicate of #16468 and #16483.

See these issues or this forum post for a temporary fix.

[intersel]

Thanks and sorry for my duplicate issue. I did search but with the wrong keywords :s