go templates: nullable foreign keys on UUIDs are not properly converted

[hhhapz]

Actual:

// Entity returns the Entity associated with the [Membership]'s (EntityID).
//
// Generated from foreign key 'memberships_entity_id_fkey'.
func (m *Membership) Entity(ctx context.Context, db DB) (*Entity, error) {
	return EntityByID(ctx, db, uuid.UUID(m.EntityID))
//                                 ↑
//                                 └─── this is invalid
}

Expected:

// Entity returns the Entity associated with the [Membership]'s (EntityID).
//
// Generated from foreign key 'memberships_entity_id_fkey'.
func (m *Membership) Entity(ctx context.Context, db DB) (*Entity, error) {
	if !m.EntityID.Valid {
		return nil, nil // (or some error)
	}
	return EntityByID(ctx, db, m.EntityID.UUID)
}

[kenshaw]

@hhhapz can you clarify if this was working properly with xo prior to the recent changes? Additionally, can you share a short schema with this? Not sure what database this is -- assuming PostgreSQL.