GitHub C2 profile malfunctioning on some situations

[armysick]

Describe the bug

For the GitHub profile to work with Athena, it is mandatory that the repository is not empty, and that the default branch is named "main".

In https://github.com/MythicAgents/Athena/blob/a2bfe4784eca50e16a68ecc242474127f4cc8d52/Payload_Type/athena/athena/agent_code/Agent.Profiles.GitHub/GitHubProfile.cs#L101 will fail unless two conditions are met:

• Repository is not empty
• Branch main exists

Expected behavior Either handle this edge case scenario (see additional data below); Or describe these two conditions as a quick note on the setup documentation.

Additional data

Stack trace for "Git Repository is empty" Exception (empty repo):

   at Octokit.Connection.RunRequest(IRequest request, CancellationToken cancellationToken, Func`2 preprocessResponseBody) in /_/Octokit/Http/Connection.cs:line 798
   at Octokit.Connection.Run[T](IRequest request, CancellationToken cancellationToken, Func`2 preprocessResponseBody) in /_/Octokit/Http/Connection.cs:line 783
   at Octokit.ApiConnection.Get[T](Uri uri, IDictionary`2 parameters)
   at Agent.Profiles.GitHub.StartBeacon()

Stack trace for "Not Found" Exception (main branch does not exist):

   at Octokit.Connection.RunRequest(IRequest request, CancellationToken cancellationToken, Func`2 preprocessResponseBody) in /_/Octokit/Http/Connection.cs:line 798
   at Octokit.Connection.Run[T](IRequest request, CancellationToken cancellationToken, Func`2 preprocessResponseBody) in /_/Octokit/Http/Connection.cs:line 783
   at Octokit.ApiConnection.Get[T](Uri uri, IDictionary`2 parameters)
   at Agent.Profiles.GitHub.StartBeacon()