prevent run time error if update failed

When trying to change contact's e-mail address to one that already exists, filed under some other contact, the update call returns "" which is decoded to null.
Contact::create() then dies with this error:
Argument 1 passed to Ctct\Components\Contacts\Contact::create() must be an array, null given

It may be that the new address must be unsubscribed, or the new address is unsubscribed and then deleted from a client which doesn't remove it from the system though. I'm not sure about the exact conditions but I'm hitting it all the time during testing.