`spwd` does not work outside `$HOME`

[amtoine]

when i cd to /tmp/, even /tmp/foo/, i get

Error: nu::shell::eval_block_with_input (link)

  × Eval block failed with pipeline input
    ╭─[scripts/shell_prompt.nu:12:1]
 12 │     $"!/($env.PWD)" |
 13 │       str replace $"!/($home)" ~ -s |
    ·       ─────┬─────
    ·            ╰── source value
 14 │       split row $sep
    ╰────

Error: nu::shell::access_beyond_end (link)

  × Row number too large (empty content).
    ╭─[scripts/shell_prompt.nu:24:1]
 24 │       $el
 25 │     } else if ($spwd_src.0 == ".") {
    ·                          ┬
    ·                          ╰── index too large (empty content)
 26 │       $".($spwd_src.1)"
    ╰────