NuGetForUnity.Cli crashes if `Environment.SpecialFolder.LocalApplicationData` is not set.

[jbvirt]

Description

I have been running this tool inside of a GitHub action and it has worked great, but we recently switched to using Kubernetes runners and suddenly this action started crashing with the error:

Unhandled exception. System.TypeInitializationException: The type initializer for 'NugetForUnity.NugetHelper' threw an exception.
 ---> System.ArgumentException: The value cannot be an empty string. (Parameter 'path')
   at System.ArgumentException.ThrowNullOrEmptyException(String argument, String paramName)
   at System.IO.Path.GetFullPath(String path)
   at NugetForUnity.NugetHelper..cctor() in /home/runner/work/NuGetForUnity/NuGetForUnity/src/NuGetForUnity/Editor/NugetHelper.cs:line 56
   --- End of inner exception stack trace ---
   at NugetForUnity.NugetHelper.set_InstallDependencies(Boolean value) in /home/runner/work/NuGetForUnity/NuGetForUnity/src/NuGetForUnity/Editor/NugetHelper.cs:line 111
   at NuGetForUnity.Cli.Program.Main(String[] args) in /home/runner/work/NuGetForUnity/NuGetForUnity/src/NuGetForUnity.Cli/Program.cs:line 55

The cause from the issue seems to be this line that is looking to get the Path.GetFullPath of Environment.SpecialFolder.LocalApplicationData. The error is caused when the LocalApplicationData folder is null or empty. This can occur in some situations where the tool is being run by the root user on Linux.

It seems like the issue will still occur in the latest version in PackageCacheManager.cs.

A workaround was to export the environment variable XDG_DATA_HOME as documented here, and make sure that the folder exists.

However, there still should either be a fallback cache path or this exception should be properly handled so that it is clear what the issue is.

• NuGetForUnity.Cli Version: 3.1.3
• Unity Version: N/A
• Operating System: Linux Container mcr.microsoft.com/dotnet/sdk:7.0

[JoC0de]

Thanks for submitting a so detailled issue.
Do you think we should handle the exception and support something like NUGET_PLUGINS_CACHE_PATH as a overwrite like documented on https://learn.microsoft.com/en-us/nuget/consume-packages/managing-the-global-packages-and-cache-folders

[jbvirt]

Yes, I think that would be a good solution.