Fix ItemCategory __str__()

src/pretix/base/models.py

@@ -562,7 +562,7 @@ class ItemCategory(Versionable):
         ordering = ('position', 'id')
 
     def __str__(self):
-        return self.name
+        return str(self.name)
 
     def delete(self, *args, **kwargs):
         super().delete(*args, **kwargs)

src/pretix/control/templates/pretixcontrol/items/index.html

@@ -19,7 +19,7 @@
 			<tr>
 				<td><strong><a href="
 				{% url "control:event.item" organizer=request.event.organizer.slug event=request.event.slug item=i.identity %}">{{ i.name }}</a></strong></td>
-				<td>{% if i.category %}{{ i.category }}{% endif %}</td>
+				<td>{% if i.category %}{{ i.category.name }}{% endif %}</td>
 			</tr>
 			{% endfor %}
 		</tbody>