fix broken api

e621.py

@@ -177,7 +177,7 @@ class E621:
         })).json()
         if 'success' in r:
             return []
-        return [E621PostVersion.from_dict(p) for p in r if p['tags']]
+        return [E621PostVersion.from_dict(p) for p in r if p.get('tags') is not None]
 
     async def get_tag_aliases(self, name: str) -> List[str]:
         data = (await self.client.get('/tag_aliases.json', params={'search[antecedent_name]': name})).json()