Check ENV variable first before doing a FS stat in settings.ddev.php

[markhalliwell]

Very minor nit, but no need to check whether the file is readable if it's not a DDEV environment.

[gitpod-io]

[plach79]

Makes sense to me

[rfay]

Could you please say why this matters?

[markhalliwell]

Logically, it just doesn't make a lot of sense to access the physical system when it can first check the environment variable which is already loaded in memory.

From a performance standpoint, I get that this isn't going to matter much. However, this code is injected into settings.php which is something that is still executed in a production environment. While one tiny is_readable call isn't going to do much, it also doesn't hurt avoiding a completely unnecessary stat() on each request when it doesn't have to.

[rfay]

I guess this is OK. One note though: settings.ddev.php is never intended to exist in a normal production environment. It's gitignored and shouldn't show up there at all.

[markhalliwell]

Thanks for the merge 😄 I am aware that settings.ddev.php shouldn't/doesn't get committed. But it would still check for one, even on prod because this was autogenerated into settings.php which is committed.