Register/Login mysqli_stmt_get_result() Error help me

Question

how can i fix this. error below

Fatal error: Uncaught Error: Call to undefined function mysqli_stmt_get_result() in /home/s6s88hqcj2py/public_html/includes/functions.inc.php:63 Stack trace: #0 /home/s6s88hqcj2py/public_html/includes/functions.inc.php(108): uidExists(Object(mysqli), 'qhewqewhqewh', 'qhewqewhqewh') #1 /home/s6s88hqcj2py/public_html/includes/girisyap.inc.php(16): girisyapUser(Object(mysqli), 'qhewqewhqewh', 'qewhqewhqew') #2 {main} thrown in /home/s6s88hqcj2py/public_html/includes/functions.inc.php on line 63

includes/functions.inc.php

<?php
error_reporting(E_ALL); ini_set('display_errors', 1);
function emptyInputKayitol($name, $email, $username, $pwd, $pwdRepeat){
 $result;
 if (  empty($name) || empty($email) || empty($username) || empty($pwd) || empty($pwdRepeat)  ) {
    $result = true;
 }
else{
$result = false;

}
return $result;
} 

function invalidUid($username){
 $result;
 if (!preg_match("/^[a-zA-Z0-9]*$/",  $username)) {
    $result = true;
 }
else{
$result = false;

}
return $result;
} 

function invalidEmail($email){
 $result;
 if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
    $result = true;
 }
else{
$result = false;

}
return $result;
} 

function pwdMatch($pwd, $pwdRepeat){
 $result;
 if ($pwd !== $pwdRepeat) {
    $result = true;
 }
else{
$result = false;

}
return $result;
} 

function uidExists($conn, $username, $email){
$sql = "SELECT * FROM users WHERE usersUid = ? OR usersEmail = ?;";
$stmt = mysqli_stmt_init($conn);

if (!mysqli_stmt_prepare($stmt, $sql)) {
    header("location: ../kayitol.php?error=stmtfailed");
    exit();
 }

 mysqli_stmt_bind_param($stmt, "ss", $username, $email);
 mysqli_stmt_execute($stmt);

 $resultData = mysqli_stmt_get_result($stmt);

 if ($row = mysqli_fetch_assoc($resultData)) {
    return $row;
 }
 else{
 $result = false;
 return $result;
 }
 mysqli_stmt_close($stmt);

} 


function createUser($conn, $name, $email, $username, $pwd){
$sql = "INSERT INTO users (usersName, usersEmail, usersUid, usersPwd) VALUES (?, ?, ?, ?);";
$stmt = mysqli_stmt_init($conn);

if (!mysqli_stmt_prepare($stmt, $sql)) {
    header("location: ../kayitol.php?error=stmtfailed");
    exit();
 }

$hashedPwd = password_hash($pwd, PASSWORD_DEFAULT);

 mysqli_stmt_bind_param($stmt, "ssss", $name, $email, $username, $hashedPwd);
 mysqli_stmt_execute($stmt);
 mysqli_stmt_close($stmt);
    header("location: ../kayitol.php?error=none");
    exit();
} 

function emptyInputGirisyap($username, $pwd){
 $result;
 if ( empty($username) || empty($pwd) ){
    $result = true;
 }
else{
$result = false;

}
return $result;
} 

function girisyapUser($conn, $username, $pwd) {
 $uidExists = uidExists($conn, $username, $username);

 if ($uidExists === false) {
    header("location: ../girisyap.php?error=wronglogin");
    exit();
 }

$pwdHashed = $uidExists["usersPwd"];
$checkPwd = password_verify($pwd, $pwdHashed);

if ($checkPwd === false) {
    header("location: ../girisyap.php");
    exit();
}
else if($checkPwd === true) {
session_start();
$_SESSION["userid"] = $uidExists["usersId"];

$_SESSION["useruid"] = $uidExists["usersUid"];
    header("location: ../index.php");
    exit();
}
}