The `$columnNames` property has a too complex type `string[]|false|null` which leads to:

1. Non-trivial to understand conditions and assertions like `if ($columnNames === false)`, `if ($columnNames === true)` and `assert(is_array($columnNames))`.
2. Avoidable [false-positives](https://scrutinizer-ci.com/g/doctrine/dbal/inspections/20d1aea4-2217-4f38-8adc-5ce10fa9cf0b/issues/files/lib/Doctrine/DBAL/Driver/Mysqli/MysqliStatement.php?status=new&orderField=path&order=asc&honorSelectedPaths=0) on Scrutinizer that thinks that `$columnNames` can be TRUE.