Email validation missing

Add a contact, enter an invalid email and hit CREATE.

The frontend alerts "Save failed", in the network tab we see the problem:

{
  "detail": "Not a valid email address.",
  "source": {
    "pointer": "/data/attributes/email"
  },
  "status": "422",
  "title": "Validation error"
}

Improvements:

• validate all fields before post
• show detailed error, when something does not work in the backend
• use the correct wording: creation has failed