Allow exporters to have empty permission

src/pretix/base/exporter.py

@@ -191,7 +191,7 @@ class BaseExporter:
         return True
 
     @classmethod
-    def get_required_event_permission(cls) -> str:
+    def get_required_event_permission(cls) -> Optional[str]:
         """
         The permission level required to use this exporter for events. For multi-event-exports, this will be used
         to limit the selection of events. Will be ignored if the ``OrganizerLevelExportMixin`` mixin is used.
@@ -206,7 +206,7 @@ class OrganizerLevelExportMixin:
         raise TypeError("required_event_permission may not be called on OrganizerLevelExportMixin")
 
     @classmethod
-    def get_required_organizer_permission(cls) -> str:
+    def get_required_organizer_permission(cls) -> Optional[str]:
         """
         The permission level required to use this exporter. Must be set for organizer-level exports. Set to `None` to
         allow everyone with any access to the organizer.

src/pretix/base/models/organizer.py

@@ -319,6 +319,9 @@ class TeamQuerySet(models.QuerySet):
     def event_permission_q(cls, perm_name):
         from ..permissions import assert_valid_event_permission
 
+        if perm_name is None:
+            return Q()
+
         if perm_name.startswith('can_') and perm_name in OLD_TO_NEW_EVENT_COMPAT:  # legacy
             return reduce(operator.and_, [cls.event_permission_q(p) for p in OLD_TO_NEW_EVENT_COMPAT[perm_name]])
         assert_valid_event_permission(perm_name, allow_legacy=False)
@@ -331,6 +334,9 @@ class TeamQuerySet(models.QuerySet):
     def organizer_permission_q(cls, perm_name):
         from ..permissions import assert_valid_organizer_permission
 
+        if perm_name is None:
+            return Q()
+
         if perm_name.startswith('can_') and perm_name in OLD_TO_NEW_ORGANIZER_COMPAT:  # legacy
             return reduce(operator.and_, [cls.organizer_permission_q(p) for p in OLD_TO_NEW_ORGANIZER_COMPAT[perm_name]])
         assert_valid_organizer_permission(perm_name, allow_legacy=False)