Gin [Feature]: ShouldBindJSON return EOF when the request body is an empty string.

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Description

ShouldBindJSON return EOF when the request body is an empty string. This error message is not friendly.

How to reproduce

package main

import (
    "fmt"

    "github.com/gin-gonic/gin"
)

type R struct {
    C string `form:"c" binding:"required"`
}

func main() {
    g := gin.Default()
    g.POST("/hello", func(c *gin.Context) {
        if err := c.BindJSON(&R{}); err != nil {
            fmt.Println(err, len(c.Errors))
        }
    })
    g.Run(":9000")
}

Expectations

$ curl --request POST '127.0.0.1:9000/hello' --data '' 

Actual result

print EOF 1.
Expect: 
`Key: 'R.C' Error:Field validation for 'C' failed on the 'required' tag 0` or `invalid request` or `empty body`

Environment

• go version:
• gin version (or commit ref):
• operating system: