[MonologBridge] FirePHPHandler::onKernelResponse throws PHP 8.1 deprecation when no user agent is set #49392
Description
Symfony version(s) affected
5.4.20 and above
Description
When no user agent is set FirePHPHandler::onKernelResponse throws
Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated
in PHP 8.1 and above
How to reproduce
I have no reproducer but it is an obvious potential problem because HeaderBag::get is allowed to return null.
Possible Solution
No response
Additional Context
No response