Users created directly in the oauth server cannot login if their user data is incorrect

[nlsvgtr]

It is possible to create a user trough the management panel with incorrect data. That user cannot login, because the API will throw errors when trying to save that user in the api.

Expected Behavior
A newly created user should be able to login.

Current Behavior
A user created in the admin site, with for example no postCode when postCode is a required field, is not able to login. The api will throw a server error: 'Ongeldige postcode'.

Possible Solution
Make sure the oauth server also validates incoming data.

Steps to Reproduce
Should be clear from the above

Detailed Description
Add validation to userdata fields in the ouath server

[ToshKoevoets]

Would preferrably also take away some of the strictness of the api.

Also empty lastname gives an error. I don't think users should be obligated to have a valid postcode to be allowed. Also the valid postcode is only in NL, so that's a bit of a limitation