Golang - Read JSON with leading white spaces or invalid characters

main.go

package main

import (
	"bufio"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"strings"
)

func main() {
	r := getReader()
	var b byte
	var leadingStr strings.Builder
	br := bufio.NewReaderSize(r, 2048)
	for {
		nextBytes, err := br.Peek(1)
		checkErr(err)
		if string(nextBytes) == "{" {
			break
		}
		b, err = br.ReadByte()
		checkErr(err)
		err = leadingStr.WriteByte(b)
		checkErr(err)
	}
	fmt.Println(leadingStr.String())
	data, err := decodeJson(br)
	checkErr(err)
	fmt.Println(data)
}

func decodeJson(r io.Reader) (map[string]string, error) {
	data := make(map[string]string)
	err := json.NewDecoder(r).Decode(&data)
	return data, err
}

func getReader() io.Reader {
	return strings.NewReader(`Some gibberish before valid json
	
	More gibberish
	
	{"hello":"world"}`)
}

func checkErr(err error) {
	if err != nil {
		log.Fatalf("%v", err)
	}
}