Notice developer about Schema class not exists

[Mte90]

I lost too many hours to understand that error... basically the query weren't working because the Schema class it wasn't executed.

https://github.com/berlindb/core/blob/master/src/Database/Query.php#L401 on this line if the class doesn't exists there aren't any notice but query without doesn't works.

[Mte90]

There are also various things in the Query on update/add that return false without noticing the developer about the error.

I had to dig in the code of BerlinDB to understand that I was using a not-existing column as example.