HandleExitCoder does not see an ExitCoder wrapped with %w #2478

What happened

HandleExitCoder looks for an ExitCoder (and for a MultiError) with a bare type assertion, so an exit error that has been wrapped with fmt.Errorf("%w") is not recognised. Nothing calls OsExiter and nothing is written to ErrWriter; the process then exits with the default code 1.

cmd.Action = func(ctx context.Context, cmd *cli.Command) error {
    return fmt.Errorf("deploy failed: %w", cli.Exit("galactic perimeter breach", 9))
}

Running that command prints nothing, and the exit code is 1 instead of 9.

Why it matters

Exit documents that the underlying error stays reachable through the standard wrapping helpers, and exitError implements Unwrap() (that is what #1090 and #2444 added). Adding context to an Action error with %w is the ordinary way to do it, and the only consumer of that promise — HandleExitCoder — did not follow.

The same happens inside a MultiError: the last exit code is read with a bare assertion, so newMultiError(errors.New("wowsa"), fmt.Errorf("...: %w", Exit("boom", 11))) exits with 1 instead of 11.

Expected

A wrapped ExitCoder should be handled exactly like an unwrapped one: the message goes to ErrWriter, OsExiter is called, and the exit code is preserved.

Environment

urfave/cli v3 (main), Go 1.27.1 on Windows. Reproduced on 2026-10-19.