Return an error message when an admin try to delete the only admin account

[monsieurswag]

I removed import { fail } from 'assert'; in "frontend/src/routes/(app)/users/[id=uuid]/edit/+page.server.ts", it seems like it was an error surely from someone who auto-imported the wrong fail function in a previous commit.

According to this Mixin definition the "name" field isn't unique which means there may multiple UserGroup object with the same name :

class NameDescriptionMixin(AbstractBaseModel):
    name = models.CharField(max_length=200, verbose_name=_("Name"), unique=False)

I am not sure having 2 user groups with the exact same name should be authorized by the application, is this normal ? If some evil user could create a user group with the same name as the admin group and bypass some permission checks. To address this potential issue in my code i always added builtin=True when fetching the admin group since builtin objects are meant to be immutable.

[eric-intuitem]

Indeed, once groups will be user-defined, we'll need to add fields_to_check = ["name"]

[monsieurswag]

Done

[monsieurswag]

Remove builtin and user_groups__builtin, and make the languageTag: languageTag synthax like it was before