Fix:(issue_2105) Ensure fish completion works

Author: dearchap

command_setup.go

@@ -88,7 +88,7 @@ func (cmd *Command) setupDefaults(osArgs []string) {
 		cmd.SuggestCommandFunc = suggestCommand
 	}
 
-	if cmd.EnableShellCompletion || cmd.Root().shellCompletion {
+	if isRoot {
 		completionCommand := buildCompletionCommand(cmd.Name)
 
 		if cmd.ShellCompletionCommandName != "" {

completion.go

@@ -30,7 +30,7 @@ var (
 			return fmt.Sprintf(string(b), appName), err
 		},
 		"fish": func(c *Command, appName string) (string, error) {
-			return c.ToFishCompletion()
+			return c.Root().ToFishCompletion()
 		},
 		"pwsh": func(c *Command, appName string) (string, error) {
 			b, err := autoCompleteFS.ReadFile("autocomplete/powershell_autocomplete.ps1")