Different behaviour from the standard library when parsing null json.Number fields

[fabiocorneti]

When parsing a json.Number that is null, the standard library will set it to an empty string, whereas go-json will return a parseFloat error.

Reproduction below:

package main

import (
	standardJson "encoding/json"

	goccyJson "github.com/goccy/go-json"
)

type Category struct {
	ID       standardJson.Number `json:"id,number"`
	ParentID standardJson.Number `json:"parent_id,number"`
}

const input = `{"id": "123", "parent_id": null}`

func main() {
	catGoccy := &Category{}
	catStandard := &Category{}
	errStandard := standardJson.Unmarshal([]byte(input), catStandard)
	if errStandard != nil {
		panic(errStandard)
	}
	errGoccy := goccyJson.Unmarshal([]byte(input), catGoccy)
	if errGoccy != nil {
		panic(errGoccy)
	}
}