New Github-hosted package causes the listing creation job to fail with a useless error message

[FairlySadPanda]

Summary
Even when following the VRC-recommended package setup steps, using the provided in-Editor tool, our trivial VRCBCE2 project crashes the list creation job.

Steps to reproduce

1. Create a new VCC repo
2. Add a newly created Github-hosted package to the githubRepos array in the repo's source.json file. The package must not have a release on Github.
3. Commit the change and wait for the Github Action to complete.

Expected outcome
The Action concludes without error.

Actual outcome
The list building job will throw the following exception:

System.ArgumentNullException: Value cannot be null. (Parameter 'collection')
     at System.Collections.Generic.List`1.InsertRange(Int32 index, IEnumerable`1 collection)
     at System.Collections.Generic.List`1.AddRange(IEnumerable`1 collection)
     at VRC.PackageManagement.Automation.Build.<get_BuildRepoListing>b__24_1() in /home/runner/work/vcc-repo/vcc-repo/ci/PackageBuilder/Build.cs:line 166
     at Nuke.Common.Execution.TargetDefinition.<>c__DisplayClass77_0.<Executes>b__0() in /_/source/Nuke.Common/Execution/TargetDefinition.cs:line 71
     at Nuke.Common.Execution.BuildExecutor.<>c.<Execute>b__4_2(Action x) in /_/source/Nuke.Common/Execution/BuildExecutor.cs:line 112
     at Nuke.Common.Utilities.Collections.EnumerableExtensions.ForEach[T](IEnumerable`1 enumerable, Action`1 action) in /_/source/Nuke.Common/Utilities/Collections/Enumerable.ForEach.cs:line 17
     at Nuke.Common.Execution.BuildExecutor.Execute(NukeBuild build, ExecutableTarget target, IReadOnlyCollection`1 previouslyExecutedTargets, Boolean failureMode) in /_/source/Nuke.Common/Execution/BuildExecutor.cs:line 112

Additional information
This will not occur if the repo has had a release.

[FairlySadPanda]

Other minor complaint: the action doesn't support the act testing tool, reporting ci/build.cmd: line 3: /mnt/f/VRChat: No such file or directory during the building job.

Being forced to use Actions remotely to test and debug is a time-consuming effort, especially as Actions endures frequent outages.

[FairlySadPanda]

I've updated this ticket with the bug format I usually follow and a clearer bug to report. This is adjacent to issue #11.