MediaPlaylist decode custom tag panic

[panda1986]

func (p *MediaPlaylist) decode(buf *bytes.Buffer, strict bool) error {
var eof bool
var line string
var err error

state := new(decodingState)
wv := new(WV)

for !eof {
	if line, err = buf.ReadString('\n'); err == io.EOF {
		eof = true
	} else if err != nil {
		break
	}

	err = decodeLineOfMediaPlaylist(p, wv, state, line, strict)
	if strict && err != nil {
		return err
	}

}
if state.tagWV {
	p.WV = wv
}
if strict && !state.m3u {
	return errors.New("#EXTM3U absent")
}
return nil

}

---

if p has customDecoder, directly decode, but state not initalized, when call decodeLineOfMediaPlaylist will panic