Fix debugprintln to forwarded stdio implementation

tools/tty/tty.go

@@ -340,16 +340,22 @@ func (self *Term) GetSize() (*unix.Winsize, error) {
 // go doesn't have a wrapper for ctermid()
 func Ctermid() string { return "/dev/tty" }
 
-func DebugPrintln(a ...any) {
+var KittyStdout = utils.Once(func() *os.File {
 	if fds := os.Getenv(`KITTY_STDIO_FORWARDED`); fds != "" {
 		if fd, err := strconv.Atoi(fds); err == nil && fd > -1 {
 			if f := os.NewFile(uintptr(fd), "<kitty_stdout>"); f != nil {
-				fmt.Fprintln(f, a...)
-				f.Close()
-				return
+				return f
 			}
 		}
 	}
+	return nil
+})
+
+func DebugPrintln(a ...any) {
+	if f := KittyStdout(); f != nil {
+		fmt.Fprintln(f, a...)
+		return
+	}
 	term, err := OpenControllingTerm()
 	if err == nil {
 		defer term.Close()