Fix

app.py

@@ -20,10 +20,11 @@ async def get_events():
 @app.post("/webhook")
 async def webhook(request: Request):
     global urls
-    event = await request.json()
+    payload = await request.json()
+    event = payload["event"]
     if event["action"] != "create":
         return
     if event["scope"] != "discussion":
         return
-    content = event["content"]
+    content = payload["comment"]["content"]
     urls += url_re.findall(content)