[BUG] branches stats fails if there are no branches in the repo

[b4rd]

API Spec link

https://learn.microsoft.com/en-us/rest/api/azure/devops/git/stats/list?view=azure-devops-rest-7.1&tabs=HTTP

API Spec version

7.1-preview.1

Describe the bug

I have a git repository with no branches.
Calling {organization}/{project}/_apis/git/repositories/{repositoryId}/stats/branches returns with a 400 error.

Expected behavior

An empty list is returned. E.g.:

{
  "count": 0,
  "value": []
}

Actual behavior

An error is returned:

{
    "$id": "1",
    "innerException": null,
    "message": "VS403403: Cannot find any branches for the reposynctest repository.",
    "typeName": "System.ArgumentException, mscorlib",
    "typeKey": "ArgumentException",
    "errorCode": 0,
    "eventId": 0
}

Reproduction Steps

• Create a repository.
• Delete all branches.
• Call the endpoint.

Environment

No response

[v-jiaodi]

@anuragc617 Please help take a look, thanks.