PDO::getAttribute may throw PDOException

[janedbal]

This is currently undocumented behaviour, example here

[SakiTakamachi]

This is also a known issue. I was a little wondering if I should just add it to the documentation, since even if I set the error mode to silent, I still get the warning.

php/php-src#12032

(edit)
However, there are other places where warnings occur even in silent mode, so it might be a good idea to add them to the documentation for now.

[Girgias]

Maybe needs to be slightly reordered to ideally be below the 80 characters by line guideline