DB query caching and php 7.2

Are you sure this is wise? It seems you could royally mess up the QB caching mechanism with that change.

Also consider that the "Error" is only a warning, and as such, it does not stop script execution. count() still returns an integer value of zero as it always has when NULL is passed as an argument. In a production environment where the PHP warning should not be displayed there will be no consequences.

The question I have for you is: What is the query that creates that condition? I suspect that's where the real problem is.