array variabe reference failing.

I have this entry in error_log on my remote site:

 PHP Notice:  Undefined variable: _globalJS in /home/jekillen/public_html/oldSite/view/classes/controlerClassGLBS.php on line 55

in controllerClassGLBS.php I have
$_globalJS = array(); // js files to be sourced throughout the site
$_globalJS[''] = '';

Why is $_globalJS not being seen?

PHP Version 7.4.27

On my local dev server is PHP Version 7.1.33
and without any change it works as expected.

This type of issue is rare for me so it is confusing

Thank you for your time and attention.

Jeff K