firebase-tools: Storage emulator does not accept multiple storage targets configuration

[REQUIRED] Environment info

firebase-tools: 9.11.0

Platform: macOS 11.3.1

[REQUIRED] Test case

Follow the steps to set up multiple storage targets: https://firebase.google.com/docs/cli/targets#set-up-deploy-target-storage-database

Ensure that the firebase.json configuration has an array of storage targets

{
 // ... your other firebase configuration
 "storage": [
    {
      "rules": "storage.rules",
      "target": "default"
    },
    {
      "rules": "our-other-target.rules",
      "target": "our-other-target"
    }
  ]
  // ... rest of configuration
}

[REQUIRED] Steps to reproduce

1. Configure multiple storage targets as described https://firebase.google.com/docs/cli/targets#set-up-deploy-target-storage-database
2. Start emulators
3. See error: Cannot start the Storage emulator without rules file specified in firebase.json: run ‘firebase init’ and set up your Storage configuration
4. Remove the array of targets and declare single target as object, not array declaration
5. Start emulators
6. Success

[REQUIRED] Expected behavior

Configuration that is acceptable for regular deployment should be acceptable for emulator.

[REQUIRED] Actual behavior

Get error when starting the emulators with multiple storage targets

Output

$ firebase emulators:start
i  emulators: Starting emulators: auth, functions, firestore, database, hosting, pubsub, storage
✔  functions: Using node@14 from host.
i  firestore: Firestore Emulator logging to firestore-debug.log
i  database: Database Emulator logging to database-debug.log
i  pubsub: Pub/Sub Emulator logging to pubsub-debug.log
i  emulators: Shutting down emulators.
i  functions: Stopping Functions Emulator
i  database: Stopping Database Emulator
i  firestore: Stopping Firestore Emulator
i  pubsub: Stopping Pub/Sub Emulator
i  auth: Stopping Authentication Emulator
i  hub: Stopping emulator hub

Error: Cannot start the Storage emulator without rules file specified in firebase.json: run 'firebase init' and set up your Storage configuration

Output with debug flags

[2021-05-20T06:58:23.662Z] > 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"]
[2021-05-20T06:58:23.663Z] > authorizing via signed-in user (dennis@oddbit.id)
i  emulators: Starting emulators: auth, functions, firestore, database, hosting, pubsub, storage {"metadata":{"emulator":{"name":"hub"},"message":"Starting emulators: auth, functions, firestore, database, hosting, pubsub, storage"}}
[2021-05-20T06:58:23.680Z] [hub] writing locator at /var/folders/d9/6zn6x8jx2_d9z478l51g275w0000gn/T/hub-cruscott---dev.json
✔  functions: Using node@14 from host. {"metadata":{"emulator":{"name":"functions"},"message":"Using node@14 from host."}}
[2021-05-20T06:58:23.717Z] defaultcredentials: writing to file /Users/dennis/.config/firebase/dennis_oddbit_id_application_default_credentials.json
[2021-05-20T06:58:23.720Z] Setting GAC to /Users/dennis/.config/firebase/dennis_oddbit_id_application_default_credentials.json {"metadata":{"emulator":{"name":"functions"},"message":"Setting GAC to /Users/dennis/.config/firebase/dennis_oddbit_id_application_default_credentials.json"}}
[2021-05-20T06:58:23.722Z] >>> [apiv2][query] GET https://firebase.googleapis.com/v1beta1/projects/cruscott---dev/adminSdkConfig [none]
[2021-05-20T06:58:24.238Z] <<< [apiv2][status] GET https://firebase.googleapis.com/v1beta1/projects/cruscott---dev/adminSdkConfig 200
[2021-05-20T06:58:24.239Z] <<< [apiv2][body] GET https://firebase.googleapis.com/v1beta1/projects/cruscott---dev/adminSdkConfig {"projectId":"cruscott---dev","databaseURL":"https://cruscott---dev.firebaseio.com","storageBucket":"cruscott---dev.appspot.com","locationId":"europe-west"}
[2021-05-20T06:58:24.271Z] Ignoring unsupported arg: projectId {"metadata":{"emulator":{"name":"firestore"},"message":"Ignoring unsupported arg: projectId"}}
[2021-05-20T06:58:24.272Z] Ignoring unsupported arg: auto_download {"metadata":{"emulator":{"name":"firestore"},"message":"Ignoring unsupported arg: auto_download"}}
[2021-05-20T06:58:24.272Z] Starting Firestore Emulator with command {"binary":"java","args":["-Dgoogle.cloud_firestore.debug_log_level=FINE","-Duser.language=en","-jar","/Users/dennis/.cache/firebase/emulators/cloud-firestore-emulator-v1.11.15.jar","--host","localhost","--port",8080,"--rules","/Users/dennis/development/Almo-Nature/agora/firestore.rules","--functions_emulator","localhost:5001"],"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/dennis/.cache/firebase/emulators/cloud-firestore-emulator-v1.11.15.jar\",\"--host\",\"localhost\",\"--port\",8080,\"--rules\",\"/Users/dennis/development/Almo-Nature/agora/firestore.rules\",\"--functions_emulator\",\"localhost:5001\"],\"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"}}
[2021-05-20T06:58:25.169Z] May 20, 2021 2:58:25 PM com.google.cloud.datastore.emulator.firestore.websocket.WebSocketServer start
INFO: Started WebSocket server on ws://localhost:64196
 {"metadata":{"emulator":{"name":"firestore"},"message":"May 20, 2021 2:58:25 PM com.google.cloud.datastore.emulator.firestore.websocket.WebSocketServer start\nINFO: Started WebSocket server on ws://localhost:64196\n"}}
[2021-05-20T06:58:25.225Z] API endpoint: http://localhost: {"metadata":{"emulator":{"name":"firestore"},"message":"API endpoint: http://localhost:"}}
[2021-05-20T06:58:25.226Z] 8080
If you are using a library that supports the FIRESTORE_EMULATOR_HOST environment variable, run:

   export FIRESTORE_EMULATOR_HOST=localhost: {"metadata":{"emulator":{"name":"firestore"},"message":"8080\nIf you are using a library that supports the FIRESTORE_EMULATOR_HOST environment variable, run:\n\n   export FIRESTORE_EMULATOR_HOST=localhost:"}}
[2021-05-20T06:58:25.226Z] 8080

Dev App Server is now running.

 {"metadata":{"emulator":{"name":"firestore"},"message":"8080\n\nDev App Server is now running.\n\n"}}
[2021-05-20T06:58:25.302Z] >>> [apiv2][query] GET https://firebase.googleapis.com/v1beta1/projects/cruscott---dev [none]
[2021-05-20T06:58:25.718Z] <<< [apiv2][status] GET https://firebase.googleapis.com/v1beta1/projects/cruscott---dev 200
[2021-05-20T06:58:25.718Z] <<< [apiv2][body] GET https://firebase.googleapis.com/v1beta1/projects/cruscott---dev {"projectId":"cruscott---dev","projectNumber":"996240691979","displayName":"Cruscott - DEV","name":"projects/cruscott---dev","resources":{"hostingSite":"cruscott---dev","realtimeDatabaseInstance":"cruscott---dev","storageBucket":"cruscott---dev.appspot.com","locationId":"europe-west"},"state":"ACTIVE"}
[2021-05-20T06:58:25.718Z] database rules config:  [{"instance":"cruscott---dev","rules":"/Users/dennis/development/Almo-Nature/agora/database.rules.json"}]
[2021-05-20T06:58:25.720Z] Ignoring unsupported arg: projectId {"metadata":{"emulator":{"name":"database"},"message":"Ignoring unsupported arg: projectId"}}
[2021-05-20T06:58:25.720Z] Ignoring unsupported arg: auto_download {"metadata":{"emulator":{"name":"database"},"message":"Ignoring unsupported arg: auto_download"}}
[2021-05-20T06:58:25.720Z] Ignoring unsupported arg: rules {"metadata":{"emulator":{"name":"database"},"message":"Ignoring unsupported arg: rules"}}
[2021-05-20T06:58:25.720Z] Starting Database Emulator with command {"binary":"java","args":["-Duser.language=en","-jar","/Users/dennis/.cache/firebase/emulators/firebase-database-emulator-v4.7.2.jar","--host","localhost","--port",9000,"--functions_emulator_host","localhost","--functions_emulator_port",5001],"optionalArgs":["port","host","functions_emulator_port","functions_emulator_host"],"joinArgs":false} {"metadata":{"emulator":{"name":"database"},"message":"Starting Database Emulator with command {\"binary\":\"java\",\"args\":[\"-Duser.language=en\",\"-jar\",\"/Users/dennis/.cache/firebase/emulators/firebase-database-emulator-v4.7.2.jar\",\"--host\",\"localhost\",\"--port\",9000,\"--functions_emulator_host\",\"localhost\",\"--functions_emulator_port\",5001],\"optionalArgs\":[\"port\",\"host\",\"functions_emulator_port\",\"functions_emulator_host\"],\"joinArgs\":false}"}}
i  database: Database Emulator logging to database-debug.log {"metadata":{"emulator":{"name":"database"},"message":"Database Emulator logging to \u001b[1mdatabase-debug.log\u001b[22m"}}
[2021-05-20T06:58:27.039Z] 14:58:27.038 [NamespaceSystem-akka.actor.default-dispatcher-5] INFO akka.event.slf4j.Slf4jLogger - Slf4jLogger started
 {"metadata":{"emulator":{"name":"database"},"message":"14:58:27.038 [NamespaceSystem-akka.actor.default-dispatcher-5] INFO akka.event.slf4j.Slf4jLogger - Slf4jLogger started\n"}}
[2021-05-20T06:58:27.176Z] 14:58:27.176 [main] INFO com.firebase.server.forge.App$ - Listening at localhost:9000
 {"metadata":{"emulator":{"name":"database"},"message":"14:58:27.176 [main] INFO com.firebase.server.forge.App$ - Listening at localhost:9000\n"}}
[2021-05-20T06:58:29.503Z] Ignoring unsupported arg: projectId {"metadata":{"emulator":{"name":"pubsub"},"message":"Ignoring unsupported arg: projectId"}}
[2021-05-20T06:58:29.504Z] Ignoring unsupported arg: auto_download {"metadata":{"emulator":{"name":"pubsub"},"message":"Ignoring unsupported arg: auto_download"}}
[2021-05-20T06:58:29.504Z] Starting Pub/Sub Emulator with command {"binary":"/Users/dennis/.cache/firebase/emulators/pubsub-emulator-0.1.0/pubsub-emulator/bin/cloud-pubsub-emulator","args":["--host=localhost","--port=8085"],"optionalArgs":["port","host"],"joinArgs":true} {"metadata":{"emulator":{"name":"pubsub"},"message":"Starting Pub/Sub Emulator with command {\"binary\":\"/Users/dennis/.cache/firebase/emulators/pubsub-emulator-0.1.0/pubsub-emulator/bin/cloud-pubsub-emulator\",\"args\":[\"--host=localhost\",\"--port=8085\"],\"optionalArgs\":[\"port\",\"host\"],\"joinArgs\":true}"}}
i  pubsub: Pub/Sub Emulator logging to pubsub-debug.log {"metadata":{"emulator":{"name":"pubsub"},"message":"Pub/Sub Emulator logging to \u001b[1mpubsub-debug.log\u001b[22m"}}
[2021-05-20T06:58:29.643Z] This is the Google Pub/Sub fake.
Implementation may be incomplete or differ from the real system.
 {"metadata":{"emulator":{"name":"pubsub"},"message":"This is the Google Pub/Sub fake.\nImplementation may be incomplete or differ from the real system.\n"}}
[2021-05-20T06:58:29.667Z] May 20, 2021 2:58:29 PM com.google.cloud.pubsub.testing.v1.Main main
INFO: IAM integration is disabled. IAM policy methods and ACL checks are not supported
 {"metadata":{"emulator":{"name":"pubsub"},"message":"May 20, 2021 2:58:29 PM com.google.cloud.pubsub.testing.v1.Main main\nINFO: IAM integration is disabled. IAM policy methods and ACL checks are not supported\n"}}
[2021-05-20T06:58:30.043Z] May 20, 2021 2:58:30 PM io.gapi.emulators.netty.NettyUtil applyJava7LongHostnameWorkaround
INFO: Unable to apply Java 7 long hostname workaround.
 {"metadata":{"emulator":{"name":"pubsub"},"message":"May 20, 2021 2:58:30 PM io.gapi.emulators.netty.NettyUtil applyJava7LongHostnameWorkaround\nINFO: Unable to apply Java 7 long hostname workaround.\n"}}
[2021-05-20T06:58:30.126Z] May 20, 2021 2:58:30 PM com.google.cloud.pubsub.testing.v1.Main main
INFO: Server started, listening on 8085
 {"metadata":{"emulator":{"name":"pubsub"},"message":"May 20, 2021 2:58:30 PM com.google.cloud.pubsub.testing.v1.Main main\nINFO: Server started, listening on 8085\n"}}
i  emulators: Shutting down emulators. {"metadata":{"emulator":{"name":"hub"},"message":"Shutting down emulators."}}
i  functions: Stopping Functions Emulator {"metadata":{"emulator":{"name":"functions"},"message":"Stopping Functions Emulator"}}
i  database: Stopping Database Emulator {"metadata":{"emulator":{"name":"database"},"message":"Stopping Database Emulator"}}
[2021-05-20T06:58:30.276Z] 14:58:30.276 [Thread-1] INFO com.firebase.server.forge.App$ - Attempting graceful shutdown.
 {"metadata":{"emulator":{"name":"database"},"message":"14:58:30.276 [Thread-1] INFO com.firebase.server.forge.App$ - Attempting graceful shutdown.\n"}}
[2021-05-20T06:58:30.281Z] 14:58:30.280 [Thread-1] INFO com.firebase.server.forge.App$ - Graceful shutdown complete.
 {"metadata":{"emulator":{"name":"database"},"message":"14:58:30.280 [Thread-1] INFO com.firebase.server.forge.App$ - Graceful shutdown complete.\n"}}
[2021-05-20T06:58:30.355Z] May 20, 2021 2:58:30 PM io.gapi.emulators.grpc.GrpcServer$3 operationComplete
INFO: Adding handler(s) to newly registered Channel.
 {"metadata":{"emulator":{"name":"pubsub"},"message":"May 20, 2021 2:58:30 PM io.gapi.emulators.grpc.GrpcServer$3 operationComplete\nINFO: Adding handler(s) to newly registered Channel.\n"}}
i  firestore: Stopping Firestore Emulator {"metadata":{"emulator":{"name":"firestore"},"message":"Stopping Firestore Emulator"}}
[2021-05-20T06:58:30.647Z] *** shutting down gRPC server since JVM is shutting down
 {"metadata":{"emulator":{"name":"firestore"},"message":"*** shutting down gRPC server since JVM is shutting down\n"}}
[2021-05-20T06:58:30.652Z] *** server shut down
 {"metadata":{"emulator":{"name":"firestore"},"message":"*** server shut down\n"}}
i  pubsub: Stopping Pub/Sub Emulator {"metadata":{"emulator":{"name":"pubsub"},"message":"Stopping Pub/Sub Emulator"}}
[2021-05-20T06:58:31.024Z] *** shutting down gRPC server since JVM is shutting down
 {"metadata":{"emulator":{"name":"pubsub"},"message":"*** shutting down gRPC server since JVM is shutting down\n"}}
[2021-05-20T06:58:31.028Z] *** server shut down
 {"metadata":{"emulator":{"name":"pubsub"},"message":"*** server shut down\n"}}
i  auth: Stopping Authentication Emulator {"metadata":{"emulator":{"name":"auth"},"message":"Stopping Authentication Emulator"}}
i  hub: Stopping emulator hub {"metadata":{"emulator":{"name":"hub"},"message":"Stopping emulator hub"}}

Error: Cannot start the Storage emulator without rules file specified in firebase.json: run 'firebase init' and set up your Storage configuration

Having trouble? Try firebase [command] --help