Description:
------------
In the test script I execute the same statement three times. The last execution has two parameters but the second parameter has array key 2 instead of 1 and is thus missing.

PDO returns false instead of throwing an exception.

Note that emulated PREPARE must be disabled.

Test script:
---------------
$host = '';
$db = '';
$user = '';
$pass = '';

$options = [
    PDO::ATTR_EMULATE_PREPARES => false, /* required */
    PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
  ];

$pdo = new PDO("mysql:host=$host; dbname=$db; charset=utf8mb4", $user, $pass, $options);

$stmt = $pdo->prepare('select ? a, ? b');

$set = [
    ['a', 'b'],
    [0 => 'a', 1 => 'b'],
    [0 => 'a', 2 => 'b'], /* Note the array keys */
  ];

foreach ($set as $params) {

    try {
        var_dump($stmt->execute($params), $stmt->fetchAll(PDO::FETCH_ASSOC));
      }
    catch (Throwable $error) {
        echo $error->getMessage() . "\n";
      }

  }


Expected result:
----------------
If emulated PREPARE is enabled, an error "SQLSTATE[HY093]: Invalid parameter number: parameter was not defined" is issued. The same error should be thrown as an exception.

Actual result:
--------------
bool(true)
array(1) {
  [0]=>
  array(2) {
    ["a"]=>
    string(1) "a"
    ["b"]=>
    string(1) "b"
  }
}
bool(true)
array(1) {
  [0]=>
  array(2) {
    ["a"]=>
    string(1) "a"
    ["b"]=>
    string(1) "b"
  }
}
bool(false)
array(0) {
}