Report packages loading failure with a specific exit-code

[podtserkovskiy]

trafficstars

The packages.Load() function can use an external package provider GOPACKAGESDRIVER for third-party build-systems like Bazel or Buck2.

Having a specific exit code when external driver fails would increase observability and will help to distinguish GOPACKAGESDRIVER's failures from other kinds of failures.

[boring-cyborg[bot]]

Hey, thank you for opening your first Pull Request !

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[podtserkovskiy]

@ldez Is there something I can do to get this PR merged?

[ldez]

I'm unsure to understand how this "increases observability and will help to distinguish GOPACKAGESDRIVER's failures from other kinds of failures". The error message is already "unique" :thinking:

Can you provide more details?