Sure, that's what I would usually do. There are two reasons to trigger the PHP warning:

1. We would hide the original problem. Perhaps `mkdir` error message contains useful information.
We could dance with `error_get_last`, but it seems too fiddly and over-complicated.

2. Given that Doctrine\Cache is quite an independent caching library, it is probably a good idea
to be as little opinionated about error handling as possible, let people handle errors how they want.
(I myself am always converting errors to \ErrorExceptions, but projects differ)