fix error USERNAME not exist in ssh-agent workaround script

[ValouBambou]

I tried the script on this page and was surprised to have it failed with the following error.

Error: nu::shell::column_not_found

  × Cannot find column 'USERNAME'
    ╭─[/home/user/.config/nushell/env.nu:27:69]
 26 │     let ssh_agent_file = (
 27 │         $nu.temp-path | path join $"ssh-agent-($env.USER? | default $env.USERNAME).nuon"
    ·                                                                     ──────┬──────┬
    ·                                                                           │      ╰── value originates here
    ·                                                                           ╰── cannot find column 'USERNAME'
 28 │     )
    ╰────

I fixed it by removing the part of the code where it defaults to the non-existing USERNAME. Maybe this var is needed in some other way, but in any case, I think this page needs to be updated.

PS: If this introduces error for other users ping me and I will update this PR

[fdncred]

I think $env.USERNAME is a windows thing so there might need to be a windows way to do it and a non-windows way to do this.

[ValouBambou]

Ok so since the right variable is checked even if the left part is not null, there is no solution using the same command. Maybe whoami is a better option here?

[ValouBambou]

I confirm it works perfectly. I will modify my PR.

[fdncred]

Thanks