Firestore emulator can access the UI, but nothing happens when interacting with it

# Issue:
I tried to run firestore on emulator but failed to interact with it.

# Reproduce:

```
$ firebase --version
9.23.0

$ mkdir test

$ cd test

$ firebase init emulators
> choose Don't set up a default project
> choose Firestore emulator
--> Choose default for every next option

$ cat firebase.json
{
"emulators": {
"firestore": {
"port": 8080
},
"ui": {
"enabled": true
}
}
}
```

```
$ firebase emulators:start --project test
i emulators: Starting emulators: firestore
⚠ firestore: Did not find a Cloud Firestore rules file specified in a firebase.json config file.
⚠ firestore: The emulator will default to allowing all reads and writes. Learn more about this option: https://firebase.google.com/docs/emulator-suite/install_and_configure#security_rules_configuration.
i firestore: Firestore Emulator logging to firestore-debug.log
i ui: Emulator UI logging to ui-debug.log

┌─────────────────────────────────────────────────────────────┐
│ ✔ All emulators ready! It is now safe to connect your app. │
│ i View Emulator UI at http://localhost:4000 │
└─────────────────────────────────────────────────────────────┘

┌───────────┬────────────────┬─────────────────────────────────┐
│ Emulator │ Host:Port │ View in Emulator UI │
├───────────┼────────────────┼─────────────────────────────────┤
│ Firestore │ localhost:8080 │ http://localhost:4000/firestore │
└───────────┴────────────────┴─────────────────────────────────┘
Emulator Hub running at localhost:4400
Other reserved ports: 4500

Issues? Report them at https://github.com/firebase/firebase-tools/issues and attach the *-debug.log files.
```

Go to the page http://localhost:4000/firestore/data and create a document. After clicking `SAVE`, nothing happens.


---
## Updated

Running with debug flag
```
firebase emulators:start --project test --debug
[2022-10-14T01:06:30.022Z] > command requires scopes: ["email","openid","https://www.googleapis.com/auth/cloudplatformprojects.readonly","https://www.googleapis.com/auth/firebase","https://www.googleapis.com/auth/cloud-platform"]
[2022-10-14T01:06:30.023Z] > authorizing via signed-in user (dbcgdhh@gmail.com)
i emulators: Starting emulators: firestore {"metadata":{"emulator":{"name":"hub"},"message":"Starting emulators: firestore"}}
[2022-10-14T01:06:30.036Z] [hub] writing locator at /var/folders/dd/p17lp6xs4370kp88pqbdx_8r0000gn/T/hub-test.json
⚠ firestore: Did not find a Cloud Firestore rules file specified in a firebase.json config file. {"metadata":{"emulator":{"name":"firestore"},"message":"Did not find a Cloud Firestore rules file specified in a firebase.json config file."}}
⚠ firestore: The emulator will default to allowing all reads and writes. Learn more about this option: https://firebase.google.com/docs/emulator-suite/install_and_configure#security_rules_configuration. {"metadata":{"emulator":{"name":"firestore"},"message":"The emulator will default to allowing all reads and writes. Learn more about this option: https://firebase.google.com/docs/emulator-suite/install_and_configure#security_rules_configuration."}}
[2022-10-14T01:06:30.053Z] Ignoring unsupported arg: projectId {"metadata":{"emulator":{"name":"firestore"},"message":"Ignoring unsupported arg: projectId"}}
[2022-10-14T01:06:30.053Z] Ignoring unsupported arg: auto_download {"metadata":{"emulator":{"name":"firestore"},"message":"Ignoring unsupported arg: auto_download"}}
[2022-10-14T01:06:30.054Z] Starting Firestore Emulator with command {"binary":"java","args":["-Dgoogle.cloud_firestore.debug_log_level=FINE","-Duser.language=en","-jar","/Users/tdak/.cache/firebase/emulators/cloud-firestore-emulator-v1.13.1.jar","--host","localhost","--port",8080],"optionalArgs":["port","webchannel_port","host","rules","functions_emulator","seed_from_export"],"joinArgs":false} {"metadata":{"emulator":{"name":"firestore"},"message":"Starting Firestore Emulator with command {\"binary\":\"java\",\"args\":[\"-Dgoogle.cloud_firestore.debug_log_level=FINE\",\"-Duser.language=en\",\"-jar\",\"/Users/tdak/.cache/firebase/emulators/cloud-firestore-emulator-v1.13.1.jar\",\"--host\",\"localhost\",\"--port\",8080],\"optionalArgs\":[\"port\",\"webchannel_port\",\"host\",\"rules\",\"functions_emulator\",\"seed_from_export\"],\"joinArgs\":false}"}}
i firestore: Firestore Emulator logging to firestore-debug.log {"metadata":{"emulator":{"name":"firestore"},"message":"Firestore Emulator logging to \u001b[1mfirestore-debug.log\u001b[22m"}}
[2022-10-14T01:06:31.022Z] Oct 14, 2022 8:06:31 AM com.google.cloud.datastore.emulator.firestore.websocket.WebSocketServer start
INFO: Started WebSocket server on ws://localhost:58177
{"metadata":{"emulator":{"name":"firestore"},"message":"Oct 14, 2022 8:06:31 AM com.google.cloud.datastore.emulator.firestore.websocket.WebSocketServer start\nINFO: Started WebSocket server on ws://localhost:58177\n"}}
[2022-10-14T01:06:31.042Z] API endpoint: http://localhost:8080 {"metadata":{"emulator":{"name":"firestore"},"message":"API endpoint: http://localhost:8080"}}
[2022-10-14T01:06:31.043Z]
If you are using a library that supports the FIRESTORE_EMULATOR_HOST environment variable, run:

export FIRESTORE_EMULATOR_HOST=localhost:8080

Dev App Server is now running.

{"metadata":{"emulator":{"name":"firestore"},"message":"\nIf you are using a library that supports the FIRESTORE_EMULATOR_HOST environment variable, run:\n\n export FIRESTORE_EMULATOR_HOST=localhost:8080\n\nDev App Server is now running.\n\n"}}
⚠ ui: Emulator UI unable to start on port 4000, starting on 4001 instead. {"metadata":{"emulator":{"name":"ui"},"message":"Emulator UI unable to start on port 4000, starting on 4001 instead."}}
[2022-10-14T01:06:31.089Z] Ignoring unsupported arg: auto_download {"metadata":{"emulator":{"name":"ui"},"message":"Ignoring unsupported arg: auto_download"}}
[2022-10-14T01:06:31.089Z] Ignoring unsupported arg: port {"metadata":{"emulator":{"name":"ui"},"message":"Ignoring unsupported arg: port"}}
[2022-10-14T01:06:31.090Z] Starting Emulator UI with command {"binary":"node","args":["/Users/tdak/.cache/firebase/emulators/ui-v1.6.4/server.bundle.js"],"optionalArgs":[],"joinArgs":false} {"metadata":{"emulator":{"name":"ui"},"message":"Starting Emulator UI with command {\"binary\":\"node\",\"args\":[\"/Users/tdak/.cache/firebase/emulators/ui-v1.6.4/server.bundle.js\"],\"optionalArgs\":[],\"joinArgs\":false}"}}
i ui: Emulator UI logging to ui-debug.log {"metadata":{"emulator":{"name":"ui"},"message":"Emulator UI logging to \u001b[1mui-debug.log\u001b[22m"}}
[2022-10-14T01:06:31.182Z] Web / API server started at localhost:4001
{"metadata":{"emulator":{"name":"ui"},"message":"Web / API server started at localhost:4001\n"}}

┌─────────────────────────────────────────────────────────────┐
│ ✔ All emulators ready! It is now safe to connect your app. │
│ i View Emulator UI at http://localhost:4001 │
└─────────────────────────────────────────────────────────────┘

┌───────────┬────────────────┬─────────────────────────────────┐
│ Emulator │ Host:Port │ View in Emulator UI │
├───────────┼────────────────┼─────────────────────────────────┤
│ Firestore │ localhost:8080 │ http://localhost:4001/firestore │
└───────────┴────────────────┴─────────────────────────────────┘
Emulator Hub running at localhost:4400
Other reserved ports: 4500

Issues? Report them at https://github.com/firebase/firebase-tools/issues and attach the *-debug.log files.
```

Debug messages after creating a document

```
[2022-10-14T01:07:16.381Z] Oct 14, 2022 8:07:16 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead
INFO: Detected non-HTTP/2 connection.
{"metadata":{"emulator":{"name":"firestore"},"message":"Oct 14, 2022 8:07:16 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead\nINFO: Detected non-HTTP/2 connection.\n"}}
[2022-10-14T01:07:16.423Z] Oct 14, 2022 8:07:16 AM com.google.cloud.datastore.emulator.firestore.websocket.WebSocketChannelHandler initChannel
INFO: Connected to new websocket client
{"metadata":{"emulator":{"name":"firestore"},"message":"Oct 14, 2022 8:07:16 AM com.google.cloud.datastore.emulator.firestore.websocket.WebSocketChannelHandler initChannel\nINFO: Connected to new websocket client\n"}}
[2022-10-14T01:07:16.476Z] Oct 14, 2022 8:07:16 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead
INFO: Detected non-HTTP/2 connection.
{"metadata":{"emulator":{"name":"firestore"},"message":"Oct 14, 2022 8:07:16 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead\nINFO: Detected non-HTTP/2 connection.\n"}}
[2022-10-14T01:07:16.588Z] Oct 14, 2022 8:07:16 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead
INFO: Detected HTTP/2 connection.
{"metadata":{"emulator":{"name":"firestore"},"message":"Oct 14, 2022 8:07:16 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead\nINFO: Detected HTTP/2 connection.\n"}}
[2022-10-14T01:07:20.178Z] Oct 14, 2022 8:07:20 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead
INFO: Detected non-HTTP/2 connection.
{"metadata":{"emulator":{"name":"firestore"},"message":"Oct 14, 2022 8:07:20 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead\nINFO: Detected non-HTTP/2 connection.\n"}}
[2022-10-14T01:07:22.199Z] Oct 14, 2022 8:07:22 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead
INFO: Detected non-HTTP/2 connection.
{"metadata":{"emulator":{"name":"firestore"},"message":"Oct 14, 2022 8:07:22 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead\nINFO: Detected non-HTTP/2 connection.\n"}}
[2022-10-14T01:07:24.220Z] Oct 14, 2022 8:07:24 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead
INFO: Detected non-HTTP/2 connection.
{"metadata":{"emulator":{"name":"firestore"},"message":"Oct 14, 2022 8:07:24 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead\nINFO: Detected non-HTTP/2 connection.\n"}}
[2022-10-14T01:07:26.241Z] Oct 14, 2022 8:07:26 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead
INFO: Detected non-HTTP/2 connection.
{"metadata":{"emulator":{"name":"firestore"},"message":"Oct 14, 2022 8:07:26 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead\nINFO: Detected non-HTTP/2 connection.\n"}}
[2022-10-14T01:07:28.265Z] Oct 14, 2022 8:07:28 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead
INFO: Detected non-HTTP/2 connection.
{"metadata":{"emulator":{"name":"firestore"},"message":"Oct 14, 2022 8:07:28 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead\nINFO: Detected non-HTTP/2 connection.\n"}}
[2022-10-14T01:07:30.283Z] Oct 14, 2022 8:07:30 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead
INFO: Detected non-HTTP/2 connection.
{"metadata":{"emulator":{"name":"firestore"},"message":"Oct 14, 2022 8:07:30 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead\nINFO: Detected non-HTTP/2 connection.\n"}}
[2022-10-14T01:07:32.298Z] Oct 14, 2022 8:07:32 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead
INFO: Detected non-HTTP/2 connection.
{"metadata":{"emulator":{"name":"firestore"},"message":"Oct 14, 2022 8:07:32 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead\nINFO: Detected non-HTTP/2 connection.\n"}}
[2022-10-14T01:07:34.244Z] Oct 14, 2022 8:07:34 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead
INFO: Detected non-HTTP/2 connection.
{"metadata":{"emulator":{"name":"firestore"},"message":"Oct 14, 2022 8:07:34 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead\nINFO: Detected non-HTTP/2 connection.\n"}}
[2022-10-14T01:07:34.315Z] Oct 14, 2022 8:07:34 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead
INFO: Detected non-HTTP/2 connection.
{"metadata":{"emulator":{"name":"firestore"},"message":"Oct 14, 2022 8:07:34 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead\nINFO: Detected non-HTTP/2 connection.\n"}}
[2022-10-14T01:07:34.366Z] Oct 14, 2022 8:07:34 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead
INFO: Detected non-HTTP/2 connection.
{"metadata":{"emulator":{"name":"firestore"},"message":"Oct 14, 2022 8:07:34 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead\nINFO: Detected non-HTTP/2 connection.\n"}}
[2022-10-14T01:07:36.338Z] Oct 14, 2022 8:07:36 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead
INFO: Detected non-HTTP/2 connection.
{"metadata":{"emulator":{"name":"firestore"},"message":"Oct 14, 2022 8:07:36 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead\nINFO: Detected non-HTTP/2 connection.\n"}}
[2022-10-14T01:07:38.362Z] Oct 14, 2022 8:07:38 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead
INFO: Detected non-HTTP/2 connection.
{"metadata":{"emulator":{"name":"firestore"},"message":"Oct 14, 2022 8:07:38 AM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead\nINFO: Detected non-HTTP/2 connection.\n"}}
```