Update main.py

main.py

@@ -1,5 +1,5 @@
 from fastapi.middleware.cors import CORSMiddleware
-from fastapi import FastAPI, Request,  Header, HTTPException, status
+from fastapi import FastAPI, Request,  Header, BackgroundTasks, HTTPException, status
 
 import json
 import os
@@ -33,14 +33,18 @@ def root():
      return {"title": "Echo Bot"}
 
 @app.post("/webhook")
-async def webhook(request: Request):
-    signature = request.headers['X-Line-Signature']
+async def webhook(
+    request: Request,
+    background_tasks: BackgroundTasks,
+    x_line_signature=Header(None),
+):
     body = await request.body()
     try:
-        line_handler.handle(body.decode(),signature)
+        background_tasks.add_task(
+            line_handler.handle, body.decode("utf-8"), x_line_signature
+        )
     except InvalidSignatureError:
-        raise HTTPException(status_code=400, detail="SignatureError")
-    
+        raise HTTPException(status_code=400, detail="Invalid signature")
     return "ok"
 
 @line_handler.add(MessageEvent, message=TextMessage)