Firestore emulator v1.14.1 regression: Unknown error returned on transaction.GetAll with an empty list of refs

### [REQUIRED] Environment info

**firebase-tools:**

firebase-tools 10.7.1 / emulator v1.14.3 fails
firebase-tools 10.5.0 / emulator v1.14.1 fails

firebase-tools 10.4.2 / emulator v1.13.1 passes

**Platform:**

Verified on both macOS and Debian Linux

### [REQUIRED] Test case

```
package main

import (
"context"
"os"

"cloud.google.com/go/firestore"
"github.com/pkg/errors"
)

func check(err error) {
if err != nil {
panic(err)
}
}

func main() {
ctx := context.Background()

if os.Getenv("FIRESTORE_EMULATOR_HOST") == "" {
panic("Not running under the firestore emulator")
}
cli, err := firestore.NewClient(ctx, "test")
check(errors.Wrap(err, "NewClient"))

refs := []*firestore.DocumentRef{}

err = cli.RunTransaction(ctx, func(ctx context.Context, tx *firestore.Transaction) error {
docs, err := tx.GetAll(refs)
if err != nil {
return errors.Wrap(err, "tx.GetAll")
}
if len(docs) > 0 {
return errors.New("expected to get zero documents")
}
return nil
})
check(errors.Wrap(err, "RunTransaction"))
}
```

### [REQUIRED] Steps to reproduce

```
go build -o demo
firebase emulators:exec --project test './demo'
```

### [REQUIRED] Expected behavior

Under firestore emulator v1.13.1 calling `GetAll` with an empty slice of refs returns a `nil` error and an empty list of documents, same behavior as the production firestore.

### [REQUIRED] Actual behavior

Under firestore emulator v1.14.1 and v1.14.3 (bundled with the latest firebase-tools release) we now get an Unknown RPC error code:

```
i Running script: ./demo
panic: RunTransaction: tx.GetAll: rpc error: code = Unknown desc =
...
Error: Script "./demo" exited with code 2
```

With full debug info:

```
firebase --debug emulators:exec --project test './demo'
[2022-04-24T23:06:54.655Z] > 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"]
[2022-04-24T23:06:54.656Z] > authorizing via signed-in user (--REDACTED--)
[2022-04-24T23:06:54.727Z] openjdk version "17.0.2" 2022-01-18

[2022-04-24T23:06:54.727Z] OpenJDK Runtime Environment Homebrew (build 17.0.2+0)
OpenJDK 64-Bit Server VM Homebrew (build 17.0.2+0, mixed mode, sharing)

[2022-04-24T23:06:54.729Z] Parsed Java major version: 17
i emulators: Starting emulators: firestore {"metadata":{"emulator":{"name":"hub"},"message":"Starting emulators: firestore"}}
[2022-04-24T23:06:54.750Z] [hub] writing locator at /var/folders/97/mchvl9w11rnbzpvfgw2j5ktm0000gn/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."}}
[2022-04-24T23:06:54.754Z] Ignoring unsupported arg: projectId {"metadata":{"emulator":{"name":"firestore"},"message":"Ignoring unsupported arg: projectId"}}
[2022-04-24T23:06:54.754Z] Ignoring unsupported arg: auto_download {"metadata":{"emulator":{"name":"firestore"},"message":"Ignoring unsupported arg: auto_download"}}
[2022-04-24T23:06:54.754Z] Starting Firestore Emulator with command {"binary":"java","args":["-Dgoogle.cloud_firestore.debug_log_level=FINE","-Duser.language=en","-jar","/Users/dgc/.cache/firebase/emulators/cloud-firestore-emulator-v1.14.1.jar","--host","localhost","--port",8083],"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/dgc/.cache/firebase/emulators/cloud-firestore-emulator-v1.14.1.jar\",\"--host\",\"localhost\",\"--port\",8083],\"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"}}
[2022-04-24T23:06:55.247Z] Apr 24, 2022 4:06:55 PM com.google.cloud.datastore.emulator.firestore.websocket.WebSocketServer start
INFO: Started WebSocket server on ws://localhost:56864
{"metadata":{"emulator":{"name":"firestore"},"message":"Apr 24, 2022 4:06:55 PM com.google.cloud.datastore.emulator.firestore.websocket.WebSocketServer start\nINFO: Started WebSocket server on ws://localhost:56864\n"}}
[2022-04-24T23:06:55.257Z] API endpoint: http:// {"metadata":{"emulator":{"name":"firestore"},"message":"API endpoint: http://"}}
[2022-04-24T23:06:55.257Z] localhost:8083
If you are using a library that supports the FIRESTORE_EMULATOR_HOST environment variable, run:

export FIRESTORE_EMULATOR_HOST=localhost:8083

Dev App Server is now running.

{"metadata":{"emulator":{"name":"firestore"},"message":"localhost:8083\nIf you are using a library that supports the FIRESTORE_EMULATOR_HOST environment variable, run:\n\n export FIRESTORE_EMULATOR_HOST=localhost:8083\n\nDev App Server is now running.\n\n"}}
i Running script: ./demo
[2022-04-24T23:06:55.266Z] Running ./demo with environment {"TERM_SESSION_ID":"w0t0p0:CC3A0B6E-323A-4ABF-B2AA-834B4CD7DA3B","SSH_AUTH_SOCK":"/Users/dgc/Library/Containers/com.maxgoedjen.Secretive.SecretAgent/Data/socket.ssh","LC_TERMINAL_VERSION":"3.4.15","COLORFGBG":"7;0","ITERM_PROFILE":"Default","XPC_FLAGS":"0x0","LANG":"en_US.UTF-8","PWD":"--REDACTED--/cmd/demo","SHELL":"/bin/zsh","__CFBundleIdentifier":"com.googlecode.iterm2","SECURITYSESSIONID":"186b7","TERM_PROGRAM_VERSION":"3.4.15","TERM_PROGRAM":"iTerm.app","PATH":"/opt/homebrew/opt/node@14/bin:/Users/dgc/go/bin:/opt/homebrew/opt/openjdk/bin:/opt/homebrew/Caskroom/google-cloud-sdk/latest/google-cloud-sdk/bin:/opt/homebrew/bin:/opt/homebrew/sbin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/opt/homebrew/opt/fzf/bin","LC_TERMINAL":"iTerm2","COLORTERM":"truecolor","COMMAND_MODE":"unix2003","TERM":"xterm-256color","HOME":"/Users/dgc","TMPDIR":"/var/folders/97/mchvl9w11rnbzpvfgw2j5ktm0000gn/T/","USER":"dgc","XPC_SERVICE_NAME":"0","LOGNAME":"dgc","LaunchInstanceID":"E33E5CCF-3AD5-4C1E-A528-49CF71A04880","__CF_USER_TEXT_ENCODING":"0x1F5:0x0:0x0","ITERM_SESSION_ID":"w0t0p0:CC3A0B6E-323A-4ABF-B2AA-834B4CD7DA3B","SHLVL":"1","OLDPWD":"--REDACTED--","HOMEBREW_PREFIX":"/opt/homebrew","HOMEBREW_CELLAR":"/opt/homebrew/Cellar","HOMEBREW_REPOSITORY":"/opt/homebrew","MANPATH":"/opt/homebrew/share/man::","INFOPATH":"/opt/homebrew/share/info:","PS1":"%n@%m %1~ $(parse_git_branch)%# ","_":"/opt/homebrew/bin/firebase","DEBUG":"true","IS_FIREBASE_CLI":"true","GCLOUD_PROJECT":"test","FIRESTORE_EMULATOR_HOST":"localhost:8083","FIREBASE_FIRESTORE_EMULATOR_ADDRESS":"localhost:8083","FIREBASE_EMULATOR_HUB":"localhost:4400"}
[2022-04-24T23:06:55.312Z] Apr 24, 2022 4:06:55 PM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead
INFO: Detected HTTP/2 connection.
{"metadata":{"emulator":{"name":"firestore"},"message":"Apr 24, 2022 4:06:55 PM io.gapi.emulators.netty.HttpVersionRoutingHandler channelRead\nINFO: Detected HTTP/2 connection.\n"}}
[2022-04-24T23:06:55.592Z] Apr 24, 2022 4:06:55 PM com.google.cloud.datastore.emulator.impl.util.WrappedStreamObserver onError
INFO: operation failed: No value present
java.util.NoSuchElementException: No value present
at java.base/java.util.Optional.get(Optional.java:143)
at com.google.cloud.datastore.emulator.impl.CloudFirestoreV1.transactionalRead(CloudFirestoreV1.java:1030)
at com.google.cloud.datastore.emulator.impl.CloudFirestoreV1.lambda$read$26(CloudFirestoreV1.java:1016)
at com.google.cloud.datastore.emulator.impl.transactions.EmulatorTransactionManager$ReadWriteTransaction.fold(EmulatorTransactionManager.java:356)
at com.google.cloud.datastore.emulator.impl.CloudFirestoreV1.read(CloudFirestoreV1.java:1014)
at com.google.cloud.datastore.emulator.impl.CloudFirestoreV1.batchGetDocuments(CloudFirestoreV1.java:397)
at com.google.cloud.datastore.emulator.impl.CloudFirestoreV1Router.batchGetDocuments(CloudFirestoreV1Router.java:126)
at com.google.cloud.datastore.emulator.firestore.v1.FirestoreV1GrpcAdapter$1.lambda$batchGetDocuments$6(FirestoreV1GrpcAdapter.java:146)
at com.google.cloud.datastore.emulator.firestore.v1.FirestoreV1GrpcAdapter.streaming(FirestoreV1GrpcAdapter.java:79)
at com.google.cloud.datastore.emulator.firestore.v1.FirestoreV1GrpcAdapter.access$100(FirestoreV1GrpcAdapter.java:41)
at com.google.cloud.datastore.emulator.firestore.v1.FirestoreV1GrpcAdapter$1.batchGetDocuments(FirestoreV1GrpcAdapter.java:146)
at com.google.firestore.v1.FirestoreGrpc$MethodHandlers.invoke(FirestoreGrpc.java:1278)
at io.grpc.stub.ServerCalls$UnaryServerCallHandler$UnaryServerCallListener.onHalfClose(ServerCalls.java:182)
at io.grpc.PartialForwardingServerCallListener.onHalfClose(PartialForwardingServerCallListener.java:35)
at io.grpc.ForwardingServerCallListener.onHalfClose(ForwardingServerCallListener.java:23)
at io.grpc.ForwardingServerCallListener$SimpleForwardingServerCallListener.onHalfClose(ForwardingServerCallListener.java:40)
at io.grpc.Contexts$ContextualizedServerCallListener.onHalfClose(Contexts.java:86)
at io.grpc.PartialForwardingServerCallListener.onHalfClose(PartialForwardingServerCallListener.java:35)
at io.grpc.ForwardingServerCallListener.onHalfClose(ForwardingServerCallListener.java:23)
at io.grpc.ForwardingServerCallListener$SimpleForwardingServerCallListener.onHalfClose(ForwardingServerCallListener.java:40)
at io.grpc.Contexts$ContextualizedServerCallListener.onHalfClose(Contexts.java:86)
at io.grpc.internal.ServerCallImpl$ServerStreamListenerImpl.halfClosed(ServerCallImpl.java:340)
at io.grpc.internal.ServerImpl$JumpToApplicationThreadServerStreamListener$1HalfClosed.runInContext(ServerImpl.java:866)
at io.grpc.internal.ContextRunnable.run(ContextRunnable.java:37)
at io.grpc.internal.SerializingExecutor.run(SerializingExecutor.java:133)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
at java.base/java.lang.Thread.run(Thread.java:833)

{"metadata":{"emulator":{"name":"firestore"},"message":"Apr 24, 2022 4:06:55 PM com.google.cloud.datastore.emulator.impl.util.WrappedStreamObserver onError\nINFO: operation failed: No value present\njava.util.NoSuchElementException: No value present\n\tat java.base/java.util.Optional.get(Optional.java:143)\n\tat com.google.cloud.datastore.emulator.impl.CloudFirestoreV1.transactionalRead(CloudFirestoreV1.java:1030)\n\tat com.google.cloud.datastore.emulator.impl.CloudFirestoreV1.lambda$read$26(CloudFirestoreV1.java:1016)\n\tat com.google.cloud.datastore.emulator.impl.transactions.EmulatorTransactionManager$ReadWriteTransaction.fold(EmulatorTransactionManager.java:356)\n\tat com.google.cloud.datastore.emulator.impl.CloudFirestoreV1.read(CloudFirestoreV1.java:1014)\n\tat com.google.cloud.datastore.emulator.impl.CloudFirestoreV1.batchGetDocuments(CloudFirestoreV1.java:397)\n\tat com.google.cloud.datastore.emulator.impl.CloudFirestoreV1Router.batchGetDocuments(CloudFirestoreV1Router.java:126)\n\tat com.google.cloud.datastore.emulator.firestore.v1.FirestoreV1GrpcAdapter$1.lambda$batchGetDocuments$6(FirestoreV1GrpcAdapter.java:146)\n\tat com.google.cloud.datastore.emulator.firestore.v1.FirestoreV1GrpcAdapter.streaming(FirestoreV1GrpcAdapter.java:79)\n\tat com.google.cloud.datastore.emulator.firestore.v1.FirestoreV1GrpcAdapter.access$100(FirestoreV1GrpcAdapter.java:41)\n\tat com.google.cloud.datastore.emulator.firestore.v1.FirestoreV1GrpcAdapter$1.batchGetDocuments(FirestoreV1GrpcAdapter.java:146)\n\tat com.google.firestore.v1.FirestoreGrpc$MethodHandlers.invoke(FirestoreGrpc.java:1278)\n\tat io.grpc.stub.ServerCalls$UnaryServerCallHandler$UnaryServerCallListener.onHalfClose(ServerCalls.java:182)\n\tat io.grpc.PartialForwardingServerCallListener.onHalfClose(PartialForwardingServerCallListener.java:35)\n\tat io.grpc.ForwardingServerCallListener.onHalfClose(ForwardingServerCallListener.java:23)\n\tat io.grpc.ForwardingServerCallListener$SimpleForwardingServerCallListener.onHalfClose(ForwardingServerCallListener.java:40)\n\tat io.grpc.Contexts$ContextualizedServerCallListener.onHalfClose(Contexts.java:86)\n\tat io.grpc.PartialForwardingServerCallListener.onHalfClose(PartialForwardingServerCallListener.java:35)\n\tat io.grpc.ForwardingServerCallListener.onHalfClose(ForwardingServerCallListener.java:23)\n\tat io.grpc.ForwardingServerCallListener$SimpleForwardingServerCallListener.onHalfClose(ForwardingServerCallListener.java:40)\n\tat io.grpc.Contexts$ContextualizedServerCallListener.onHalfClose(Contexts.java:86)\n\tat io.grpc.internal.ServerCallImpl$ServerStreamListenerImpl.halfClosed(ServerCallImpl.java:340)\n\tat io.grpc.internal.ServerImpl$JumpToApplicationThreadServerStreamListener$1HalfClosed.runInContext(ServerImpl.java:866)\n\tat io.grpc.internal.ContextRunnable.run(ContextRunnable.java:37)\n\tat io.grpc.internal.SerializingExecutor.run(SerializingExecutor.java:133)\n\tat java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)\n\tat java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)\n\tat java.base/java.lang.Thread.run(Thread.java:833)\n\n"}}
panic: RunTransaction: tx.GetAll: rpc error: code = Unknown desc =

goroutine 1 [running]:
main.check(...)
--REDACTED--/demo/main.go:13
main.main()
--REDACTED--/demo/main.go:38 +0x100
⚠ Script exited unsuccessfully (code 2)
i emulators: Shutting down emulators. {"metadata":{"emulator":{"name":"hub"},"message":"Shutting down emulators."}}
i firestore: Stopping Firestore Emulator {"metadata":{"emulator":{"name":"firestore"},"message":"Stopping Firestore Emulator"}}
[2022-04-24T23:06:56.111Z] *** shutting down gRPC server since JVM is shutting down
{"metadata":{"emulator":{"name":"firestore"},"message":"*** shutting down gRPC server since JVM is shutting down\n"}}
[2022-04-24T23:06:56.124Z] *** server shut down
{"metadata":{"emulator":{"name":"firestore"},"message":"*** server shut down\n"}}
i hub: Stopping emulator hub {"metadata":{"emulator":{"name":"hub"},"message":"Stopping emulator hub"}}

Error: Script "./demo" exited with code 2

Having trouble? Try again or contact support with contents of firebase-debug.log
```