Avoid the rare fetch error in Svelte server

[albertsgarde]

To reproduce, simply send many requests to the frontend very quickly. The stress test script can be used.

An example of the error log is as follows

TypeError: fetch failed
    at fetch (file:///home/albert/deepdecipher/frontend/build/shims.js:20346:13)
    at async load (file:///home/albert/deepdecipher/frontend/build/server/chunks/8-19d6d154.js:15:20)
    at async load_server_data (file:///home/albert/deepdecipher/frontend/build/server/index.js:1867:18)
    at async file:///home/albert/deepdecipher/frontend/build/server/index.js:3277:18 {
  cause: SocketError: other side closed
      at Socket.onSocketEnd (file:///home/albert/deepdecipher/frontend/build/shims.js:8835:24)
      at Socket.emit (node:events:526:35)
      at endReadableNT (node:internal/streams/readable:1359:12)
      at process.processTicksAndRejections (node:internal/process/task_queues:82:21) {
    code: 'UND_ERR_SOCKET',
    socket: {
      localAddress: '127.0.0.1',
      localPort: 5086,
      remoteAddress: undefined,
      remotePort: undefined,
      remoteFamily: undefined,
      timeout: undefined,
      bytesWritten: 14043,
      bytesRead: 44649042
    }
  }
}