chore: remove occurrences of empty()

[alexandre-daubois]

empty() is used less and less in favor of bool casts on arrays. Symfony, for example, banned it from its codebase. I suggest we remove them from here as well.

[DZunke]

May i ask why those bool casts are favored instead of replacing empty by explicit checks? I understand the downsides of empty but it feels weared to check if an empty array is false instead of explicit check like \count($foo) === 0.

I just try to understand the pro and con of this variant 🤔

[alexandre-daubois]

I'm in favor of removing empty(), but I'm also fine using \count($foo) === 0 to check array emptiness. The main difference is that by using a bool cast, this check is performed at the engine level instead of userland, which makes it more efficient. I can understand performance in not what matters the most here, and I can update the PR to use count() if you prefer. As long as empty() is avoided 😄