Description:
------------
json with "\0000token" causes fatal error when decoding $assoc=true, however it passes with $assoc=false.

it should return NULL and set json_last_error flag:

➔ php56 t.php 
int(1)
array(1) {
  ["foo"]=>
  array(1) {
    ["l"]=>
    array(1) {
      ["uid"]=>
      string(0) ""
    }
  }
}
PHP Fatal error:  Cannot access property started with '\0' in t.php on line 4
➔ cat t.php 
<?php

var_dump(1, json_decode('{"foo": {"\u0000l": {"uid":""} } }', true));
var_dump(2, json_decode('{"foo": {"\u0000l": {"uid":""} } }', false));
➔