Custom commented column type removal causes unknown column type exception

Problem happens when initially, as example, there was commented type "foo" registered and used:

Doctrine\DBAL\Types\Type::addType('foo', 'FooType');
$em->getConnection()
    ->getDatabasePlatform()
    ->markDoctrineTypeCommented(Doctrine\DBAL\Types\Type::getType('foo'));

When the type usage and declaration is removed, the database schema upgrade fails.
This is because DBAL reads the comment from the database and tries to find the type 'foo'.

I suggest ignoring the database column comment and stick to the standard type recognition in case the type is not declared.