readMessagePayload may return (nil, nil)

[urey-hiker]

	// Got entire RTMP message?
	if int(chunk.message.payloadLength) == len(chunk.message.Payload) {
		m = chunk.message
		chunk.message = nil
	}

	return

When we did not got the entire RTMP message, readMessagePayload will return (nil, nil).
which cause onMessageArrivated got a nil message.

		if m, err = v.readMessagePayload(chunk); err != nil {
			return
		}

		if err = v.onMessageArrivated(m); err != nil {
			return
		}

May I create a new error variable? var errTryAgain = errors.New("Try again")

[winlinvip]

If we use system error, it seems ok to use errTryAgain. But if we use go-oryx-lib/errors to return and generate error, maybe it's not so good enough, because it will generate error with callstack, right?

So, I think it's ok to return nil,nil and we just need to add a comment to the API for this special situation.

[winlinvip]

I use complex errors(go-oryx-lib/errors) in RTMP, and remove the system simple errors, please read cba071e

For AMF0, we already used the complex errors, please read

go-oryx-lib/amf0/amf0.go

Line 157 in cba071e

return nil, oe.Errorf("Marker %v is not supported", m)

[urey-hiker]

OK, I will check complex errors.

The return of nil, nil will make onMessageArrivated ran into panic.

v.onMessageArrivated(m *Message)->v.DecodeMessage(m *Message)->p := m.Payload[:]

[winlinvip]

Please file a PR to fix the panic.