array_merge(): argument #2 must be type array, null given

I'm a little bit frustrated. I stumble from one problem to the next.
My configuration:
- Joomla 5.2.5
- PHP 8.4
- JEM 4.4.2
After i've solved the problems on the administration side, I get the error message
"0-array_merge(): argument #2 must be type array, null given"
everytime, when I request information of one of the venues.
https://[host]/index.php?option=com_jem&view=venue&id=xyz

I've turned the $debug option int the configuration.php file to 'true'. but there is no PHP call stack produced.

Can somebody give me a hint, where to check for the source of the bug?

Best regards
hike39

You can fix it by checking the JEM configuration value for locked venue access levels. Run this query in your Joomla database, replacing #__ with your real table prefix:

UPDATE #__jem_config
SET value = '["1"]'
WHERE keyname = 'access_level_locked_venues';

If the row does not exist, insert it:

INSERT INTO #__jem_config (keyname, value, access)
VALUES ('access_level_locked_venues', '["1"]', '0');

The error is caused by PHP 8.4 being stricter: JEM 4.4.2 tries to merge access levels, but if is empty or invalid, json_decode()[/code] returns null, causing: --> [code]array_merge(): argument #2 must be type array, null given

Tell me if this fixs it. 

just to note:

-> How did you upgrade/install to 4.4.2? 
was it a clean install and import data. or did you update JEM files by normal update path;
or something else? 

THX a lot. Your instruction solved my problem. 
Greetings
hike39

I updated the extension.