Fixed posting a message without sticker

boards/models/attachment/__init__.py

@@ -55,7 +55,10 b' class AttachmentManager(models.Manager):'
         return attachment
 
     def get_by_alias(self, name):
-        return AttachmentSticker.objects.get(name=name).attachment
+        try:
+            return AttachmentSticker.objects.get(name=name).attachment
+        except AttachmentSticker.DoesNotExist:
+            return None
 
     def _compare_chunks(self, chunks1, chunks2):
         """