Symfony version(s) affected: 5.4

Description
At the moment cache is used this way:

It's a classical example of https://en.wikipedia.org/wiki/Time-of-check_to_time-of-use

Nothing guarantees the cache that is valid in line 48 is not valid anymore in line 52

If it happens you'd get Warning: hash_equals(): Expected known_string to be a string, null given

How to reproduce
For obvious reasons it's super hard to reproduce it without touching code, but simply make a getItem return nothing (as if it didn't find the value). Alternatively - with a debugger just step on the line 52 and wait til it expires.

Possible Solution
Just using $this->cache->getItem($cacheKey); is sufficient, without extra hasItem check.