Fix validation for claim 'trial_cracked_at' field
Fix validation for claim 'trial_cracked_at' field

If the case type is not set, there's no way to know if this field is
required or not, so it shouldn't be erroring.

ministryofjustice/advocate-defence-payments,ministryofjustice/advocate-defence-payments,ministryofjustice/advocate-defence-payments,ministryofjustice/advocate-defence-payments