遇到一个关于php7 json_decode null问题！

        $some_string = htmlspecialchars_decode($some_string);
        $some_string = preg_replace("/\t/", " ", $some_string);
        $some_string = preg_replace("/\n/", ' ', $some_string);
        $some_string = str_replace("\n", ' ', $some_string);
        $some_string = str_replace ('\n','', $some_string);

<?php 
$jsonStr1 = &#39;{status: {RetCode:0, msg: "success"}, data: {}}&#39;;
var_dump(json_decode($jsonStr1, true));
var_dump(json_last_error());
echo "--------分割线--------".PHP_EOL;
$jsonStr2 = &#39;{"status": {"RetCode":0, "msg": "success"}, "data": {}}&#39;;
var_dump(json_decode($jsonStr2, true));

NULL
int(4)
--------分割线--------
array(2) {
  ["status"]=>
  array(2) {
    ["RetCode"]=>
    int(0)
    ["msg"]=>
    string(7) "success"
  }
  ["data"]=>
  array(0) {
  }
}

$dataString = $merchant_arr['data'];
$A = substr($dataString, 0, 1);
$B = substr($dataString, 1, 1);
$C = substr($dataString, 2, 1);
if ((ord($A) == 239) && (ord($B) == 187) && (ord($C) == 191)) {
    $dataString = substr($dataString, 3);
}
$dataArray = json_decode($dataString, true);