Type error when data from database is incompatible with mapping

[alcaeus]

This is the root cause for the issue described in doctrine/DoctrineMongoDBBundle#564: a property was mapped as an embedded document, but the data received from the database was a scalar value. In order to avoid type errors, the hydration logic needs to better assert expected types.

[malarzm]

FWIW have no idea we can fail gracefully if we expect an object and get a scalar. Unless more gracefully as throw an exception instead of a type error? :)

[alcaeus]

Fixed in #2073