When data is imported from the NK15, prevent users whenever some aliases are deleted

apps/note/models/notes.py

@@ -222,7 +222,7 @@ class Alias(models.Model):
     normalized_name = models.CharField(
         max_length=255,
         unique=True,
-        default='',
+        blank=False,
         editable=False,
     )
     note = models.ForeignKey(
@@ -257,6 +257,8 @@ class Alias(models.Model):
         if len(normalized_name) >= 255:
             raise ValidationError(_('Alias is too long.'),
                                   code='alias_too_long')
+        if not normalized_name:
+            raise ValidationError(_('This alias contains only complex character. Please use a more simple alias.'))
         try:
             sim_alias = Alias.objects.get(normalized_name=normalized_name)
             if self != sim_alias:

note_kfet/templates/scripts/mail-error500.html

@@ -1,2 +0,0 @@
-{# The data is already sent as HTML, so we return only the HTML data. Devs don't need a pretty mail... #}
-{{ error }}

note_kfet/templates/scripts/mail-error500.txt

@@ -1,7 +0,0 @@
-Une erreur est survenue dans la Note Kfet. Les détails sont ci-dessous.
-
-Cordialement,
-
-L'équipe de la Note Kfet.
-
-{{ error }}