Bash install script fails with 'unbound variable' on MacOS 13 installing .NET Core 2.1/3.0/3.1

[nike4613]

See CI logs here: https://github.com/MonoMod/MonoMod/actions/runs/15600404522/job/43940467553?pr=240

Running 'bash /Users/runner/work/_actions/nike4613/install-dotnet/533307d1c90c37993c8ef1397388bc9783e7b87c/dotnet-install.sh --skip-non-versioned-files --no-path --channel 3.1 --architecture x64 --runtime dotnet --install-dir /Users/runner/.dotnet'
/Users/runner/work/_actions/nike4613/install-dotnet/533307d1c90c37993c8ef1397388bc9783e7b87c/dotnet-install.sh: line 1440: link_types[$link_index]: unbound variable

This only started a few weeks ago. As far as I can tell, there have been no new script versions since then. It only happens for .NET Core 2.1, 3.0, and 3.1, and only when installing to a MacOS 13 x86_64 runner.

[baronfel]

We believe this is a duplicate of #610, which the team is looking at now.