VISUAL, EDITOR, SUDO_EDITOR env vars fail with --switches

Bug report form

• I have done a basic search of the issue tracker to find any existing issues that are similar.
• I have checked that my version is at least the latest stable release available via my installation method.

Describe the bug

Long story short: this should not be necessary / automatic. When these variables are set as strings, as they just ARE. Nushell fails on them. Nushell expect a list of strings for commands with flags or subcommands. But in these cases It's not very intuitive

#env.nu

# Fix for broken editor integration in Nushell.
#
# Our environment exports VISUAL/EDITOR as a command plus arguments (e.g.
# "codium --wait"), which zsh splits implicitly but Nushell treats as a single
# program name. Nushell's built-in `config` command (and similar) expect the
# editor as a list like ['codium', '--wait'], so split on spaces and keep the
# command together with all its switches.
$env.EDITOR      = ($env.EDITOR? | default "nano"          | str trim | split row " " | where {|el| $el != "" })
$env.VISUAL      = ($env.VISUAL? | default "codium --wait" | str trim | split row " " | where {|el| $el != "" })
$env.SUDO_EDITOR = ($env.VISUAL? | default "codium --wait" | str trim | split row " " | where {|el| $el != "" })

How to reproduce

❯ $env.VISUAL = "codium --wait"

~ 
❯ config nu
Error: nu::shell::external_command

  × External command failed
   ╭─[repl_entry #10:1:1]
 1 │ config nu
   · ────┬────
   ·     ╰── `codium --wait` not found
   ╰────
  help: Failed to find the editor executable


~ 
❯ 

~ 
❯ $env.VISUAL = [ "codium" "--wait" ]

~ 
❯ config nu # works

Expected behavior

Nushell expect a list of strings for commands with flags or subcommands. But in these cases It's not very intuitive

Configuration

version | transpose key value | to md --pretty

Start by tracing the config nu command's editor lookup for VISUAL, EDITOR, and SUDO_EDITOR, using the reproduction with codium --wait. Determine how string-valued environment variables are handled versus lists, then verify that editor commands containing switches work without manual conversion.