From 2e0592b0a68b11a5a14ed9f2de134204bf733b09 Mon Sep 17 00:00:00 2001
From: Raphael Michel <michel@rami.io>
Date: Tue, 14 Sep 2021 15:02:06 +0200
Subject: [PATCH] API: Fix crash on invalid input (PRETIXEU-5A9)

---
 src/pretix/base/models/items.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/pretix/base/models/items.py b/src/pretix/base/models/items.py
index 07b95bff82..0c7dd9fd53 100644
--- a/src/pretix/base/models/items.py
+++ b/src/pretix/base/models/items.py
@@ -1620,6 +1620,8 @@ class Quota(LoggedModel):
 
     @staticmethod
     def clean_items(event, items, variations):
+        if not items:
+            return
         for item in items:
             if event != item.event:
                 raise ValidationError(_('One or more items do not belong to this event.'))