It’s similar to something i’ve come across before, but with people using Plesk.
We had code that was using a Bricks’ class (PHP class, not CSS class) and even though we knew the order that the code was executing was correct, and that the class must exist at the time the code was executing, (it was impossible for the plugin to be active without Bricks being active, and the code always ran after Bricks) Plesk still had an issue with it and threw an error saying the class didn’t exist.
I don’t use these platforms, but it seems whatever they’re doing. they’re going through and checking the code for errors, but not taking into account the order in which the code would be fired on the actual site. So errors are shown that aren’t actually errors on the site. For example, the error in your log says “PHP Fatal error”. If there was actually a real fatal error you would have known about it as it would have crashed the page and just white screen, it wouldn’t just be in the log.
So always checking functions and classes exist before using seems vital if using these platforms, even if you know 100% know the order is correct.