A bit silly, but a dataclass with a field of type None (or de/serializing something with NoneType itself) errors.
from databind.json import dump, load
load(None, None)
# NoMatchingConverter: no deserializer for `TypeHint(NoneType)` and payload of type `NoneType`
dump(None, None)
# NoMatchingConverter: no serializer for `TypeHint(NoneType)` and payload of type `NoneType`
Is this intentional or an oversight?