问函数在调用时返回错误

EN

<?php 
function getmenuitems($menu) {

$query = "SELECT * FROM `menu` WHERE `item_cat`= '" .$menu. "' ";
$result = $mysqli->query($query) or die($mysqli->error.__LINE__);


    if($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
        $item_name = stripslashes($row['item_name']);
        $item_des = stripslashes($row['item_des']);
        $item_price = stripslashes($row['item_price']);     
     ?>
<div class="menu_contain">
  <div class="order-menu-first">
    <div class="mp"><strong><?php echo $item_name; ?></strong> <?php echo $item_des; ?>        </div>
  </div>
  <div class="order-menu-second">
    <div class="mp">
      <select>
        <option value="1">1</option>
        <option value="2">2</option>
        <option value="3">3</option>
        <option value="4">4</option>
        <option value="5">5</option>
        <option value="6">6</option>
        <option value="7">7</option>
        <option value="8">8</option>
        <option value="9">9</option>
        <option value="10">10</option>
        <option value="11">11</option>
        <option value="12">12</option>
        <option value="13">13</option>
        <option value="14">14</option>
        <option value="15">15</option>
        <option value="16">16</option>
        <option value="17">17</option>
        <option value="18">18</option>
        <option value="19">19</option>
        <option value="20">20</option>
        <option value="21">21</option>
        <option value="22">22</option>
        <option value="23">23</option>
        <option value="24">24</option>
        <option value="25">25</option>
      </select>
    </div>
  </div>
  <div class="order-menu-third">
    <div class="mp">
      <input type="text" value="notes">
    </div>
  </div>
  <div class="order-menu-third">
    <div class="mp"> <?php echo $item_price; ?> </div>
  </div>
  <div class="order-menu-fifth">
    <div class="mp"> <a href="#">X</a> </div>
  </div><div class="clear"></div> 

  <?php 
echo getmenuitems('firsts');
   ?>