Add extra debug log for ssh-agent issues

[Nezteb]

Why do you need this?

• I have talked about this in a separate issue (required)

Description

I was having issues in #417 specifically with Nushell (nu).

In order to diagnose the issue I cloned k3sup locally and added a error log statement that helped me diagnose the problem, hence this PR.

It turns out the issue was because I had this in my config.nu:

# Bad
$env.SSH_AUTH_SOCK = "/Users/noah/Library/Group Containers/2BUA8C4S2C.com.1password/t/agent.sock"

# Good
$env.SSH_AUTH_SOCK = `/Users/noah/Library/Group Containers/2BUA8C4S2C.com.1password/t/agent.sock`

Apparently in Nushell, backticks are the appropriate delimiter for paths that contains spaces in the name.

How Has This Been Tested?

I tested locally with good and bad Nushell SSH_AUTH_SOCK definitions.

Types of changes

• Logging update (non-breaking change that improves DX)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have signed-off my commits with git commit -s
• I have added tests to cover my changes.
• All new and existing tests passed.

[derek]

Thank you for your contribution. unfortunately, one or more of your commits are missing the required "Signed-off-by:" statement. Signing off is part of the Developer Certificate of Origin (DCO) which is used by this project.

Read the DCO and project contributing guide carefully, and amend your commits using the git CLI. Note that this does not require any cryptography, keys or special steps to be taken.

💡 Shall we fix this?

This will only take a few moments.

First, clone your fork and checkout this branch using the git CLI.

Next, set up your real name and email address:

git config --global user.name "Your Full Name"
git config --global user.email "you@domain.com"

Finally, run one of these commands to add the "Signed-off-by" line to your commits.

If you only have one commit so far then run: git commit --amend --signoff and then git push --force.
If you have multiple commits, watch this video.

Check that the message has been added properly by running "git log".

[Nezteb]

@alexellis Hello! Are you still interested in merging this? If not, no worries at all. 😄