Exception - count(): Argument #1 ($value) must be of type Countable|array, null given

Error code: generalexceptionmessage

• line 4599 of /h5p/h5plib/v124/joubel/core/h5p.classes.php: TypeError thrown
• line 4599 of /h5p/h5plib/v124/joubel/core/h5p.classes.php: call to count()
• line 4717 of /h5p/h5plib/v124/joubel/core/h5p.classes.php: call to Moodle\H5PContentValidator->validateGroup()
  .......

A PHP 8 issue:
https://www.php.net/manual/en/function.count.php
"8.0.0    count() will now throw TypeError on invalid countable types passed to the value parameter."