[Mailer] Handle null error_get_last() to prevent array offset error on SMTP auth failure #59351
Description
Symfony version(s) affected
6.4.13
Description
Since #53157, when we attempt to send an email and SMTP fails to authenticate due to an unexpected response code (e.g. "Too many failed login attempts"), it attempts to retrieve an error message from the error_get_last() function, even if the returned value is null. This results in an Trying to access array offset on value of type null error, rather than providing an explanation as to why an email was not sent.
How to reproduce
I'll try to make a reproducer in the next few days if it's still needed
Possible Solution
From my internal testing, only throwing $this->getReadConnectionDescription() when error_get_last() equals null correctly fallbacks to a correct error message.
Additional Context
No response