Suppress spurious RequestAborted ASGI errors on the admin panel

Unsure why this error triggers on every request to the Django admin
panel these days but all the requests are completing fine and the
client is clearly not aborting the request when the RequestAborted
exception is raised.

Suppress these errors for now via middleware to prevent them from
unnecessarily cluttering up the server logs and confusing folks.

Related #1152

src/khoj/configure.py

@@ -13,7 +13,7 @@ from asgiref.sync import sync_to_async
 from django.conf import settings
 from django.db import close_old_connections, connections
 from django.utils.timezone import make_aware
-from fastapi import Response
+from fastapi import Request, Response
 from starlette.authentication import (
     AuthCredentials,
     AuthenticationBackend,
@@ -26,7 +26,7 @@ from starlette.middleware.authentication import AuthenticationMiddleware
 from starlette.middleware.base import BaseHTTPMiddleware
 from starlette.middleware.httpsredirect import HTTPSRedirectMiddleware
 from starlette.middleware.sessions import SessionMiddleware
-from starlette.requests import HTTPConnection
+from starlette.requests import ClientDisconnect, HTTPConnection
 from starlette.types import ASGIApp, Receive, Scope, Send
 
 from khoj.database.adapters import (
@@ -355,8 +355,19 @@ def configure_middleware(app, ssl_enabled: bool = False):
             super().__init__(app)
             self.app = app
 
+    class SuppressClientDisconnectMiddleware(BaseHTTPMiddleware):
+        async def dispatch(self, request: Request, call_next):
+            try:
+                return await call_next(request)
+            except ClientDisconnect:
+                logger.debug("Client disconnected before response completion.")
+                # Return a minimal response to potentially satisfy the ASGI server
+                # and prevent further error logging.
+                return Response(status_code=499)
+
     if ssl_enabled:
         app.add_middleware(HTTPSRedirectMiddleware)
+    app.add_middleware(SuppressClientDisconnectMiddleware)
     app.add_middleware(AsyncCloseConnectionsMiddleware)
     app.add_middleware(AuthenticationMiddleware, backend=UserAuthenticationBackend())
     app.add_middleware(NextJsMiddleware)