The links in convertException gives 404, i'm not 100% if I updated them correct, or if the e.g. should be update to 8.0 already.

https://dev.mysql.com/doc/refman/8.0/en/server-error-reference.html
https://dev.mysql.com/doc/refman/8.0/en/client-error-reference.html

This will allow for subsequent fetches in different modes.

This return type is conditional to $params['wrapperClass']. Luckily,
recent versions of Psalm allow documenting it properly.
See https://github.com/vimeo/psalm/issues/3277

Note that phpstan is not able to understand this yet, but still attempts
to, hence the extra ignore rules.

Not all RDBMS have a concept of database, apparently (see SQLAnywhere).
Those who do not should pass in a string to stay compatible with the
signature.