JSON iter doesn't work properly with nil RawMessage

[mjnovice]

package main

import (
	"encoding/json"
	"fmt"

	jsoniter "github.com/json-iterator/go"
)

func main() {
	type A struct {
		Rm jsoniter.RawMessage
	}

	a := A{}
	b, e := jsoniter.Marshal(a)
	fmt.Println("jsoniter: ",b, e)
	e = jsoniter.Unmarshal(b, &a)
	fmt.Println("jsoniter: ",e)

	b, e = json.Marshal(a)
	fmt.Println("json: ",b, e)
	e = json.Unmarshal(b, &a)
	fmt.Println("json: ",e)
}

https://play.golang.org/p/RoBEyZNxk-R

[funny-falcon]

Fully symmetric comparison validates issue:
https://play.golang.org/p/ydVcBDQsF5l

[NOMORECOFFEE]

Hello. It's brake behavior to unmarshal null value into RawMessage

https://play.golang.org/p/xDrMSSKyisZ

[tiit-clarifai]

@AllenX2018 As mentioned by the preceding commenter, the changes introduced in 5bce16d broke compatibility with unmarshaling of null into a RawMessage: the result is a nil byte slice, but the standard library would store the bytes null instead.

Would it be possible to address this issue?