[searx] broken pipe

[billietl]

First of all, here if my configuration :
docker-compose.yml :

---
version: '2'
services:
  web:
    build:
      context: .
      dockerfile: nginx.dockerfile
    ports:
      - 80
    links:
      - app
    environment:
      SERVICE_80_NAME: "search"
      SERVICE_80_CHECK_HTTP: "/"
      SERVICE_80_CHECK_INTERVAL: "60s"
      SERVICE_80_TAGS: "web"
  app:
    image: wonderfall/searx
    environment:
      IMAGE_PROXY: "True"
      BASE_URL: "https://search.louis.mushland.xyz"

nginx vhost conf :

user www-data;

events {
  worker_connections 768;
}

http {
  include /etc/nginx/mime.types;
  default_type application/octet-stream;

  server {
    listen 80;
    
    location / {
      proxy_pass http://app:8888;
      proxy_set_header        Host                 $host;
      proxy_set_header        X-Real-IP            $remote_addr;
      proxy_set_header        X-Forwarded-For      $proxy_add_x_forwarded_for;
      proxy_set_header        X-Remote-Port        $remote_port;
      proxy_set_header        X-Forwarded-Proto    $scheme;
      proxy_redirect          off;
    }
  }
}

While navigating using firefox I randomly get 499 errors, and searx has this message in the logs :

Traceback (most recent call last):
  File "/usr/lib/python2.7/SocketServer.py", line 596, in process_request_thread
    self.finish_request(request, client_address)
  File "/usr/lib/python2.7/SocketServer.py", line 331, in finish_request
    self.RequestHandlerClass(request, client_address, self)
  File "/usr/lib/python2.7/SocketServer.py", line 654, in __init__
    self.finish()
  File "/usr/lib/python2.7/SocketServer.py", line 713, in finish
    self.wfile.close()
  File "/usr/lib/python2.7/socket.py", line 283, in close
    self.flush()
  File "/usr/lib/python2.7/socket.py", line 307, in flush
    self._sock.sendall(view[write_offset:write_offset+buffer_size])
error: [Errno 32] Broken pipe

Since I don't know if it comes from the docker image or the application itself, and that I don't know how it runs, I first post here for help.
Have I done something wrong ?