catch integrityerrors in editor

src/c3nav/editor/views/edit.py

@@ -1,5 +1,6 @@
 import typing
 from contextlib import suppress
+from sqlite3 import IntegrityError
 
 from django.contrib import messages
 from django.contrib.auth.views import redirect_to_login
@@ -289,8 +290,11 @@ def edit(request, pk=None, model=None, level=None, space=None, on_top_of=None, e
 
             with request.changeset.lock_to_edit(request) as changeset:
                 if changeset.can_edit(request):
+                    try:
                         obj.save()
-
+                    except IntegrityError:
+                        messages.error(request, _('Duplicate entry.'))
+                    else:
                         if form.redirect_slugs is not None:
                             for slug in form.add_redirect_slugs:
                                 obj.redirects.create(slug=slug)