PHP上传文件错误

Question

我正在尝试在本地Firebase中使用php。但是，当我单击按钮时，我的php脚本已下载。这是我的代码

    <div id="popover-head" class="hide">
        Unggah berkas disini
    </div>
    <div id="popover-content" class="hide">
   <form action="save.php" method="post" enctype="multipart/form-data">
      <input type="file" name="file">
      <input type="submit" name="upload" value="Upload">
    </form>
    </div>

这是我的php文件

<?php

if($_POST['upload']){
            $ekstensi_diperbolehkan = array('png','jpg');
            $nama = $_FILES['file']['name'];
            $x = explode('.', $nama);
            $ekstensi = strtolower(end($x));
            $ukuran = $_FILES['file']['size'];
            $file_tmp = $_FILES['file']['tmp_name'];    

            if(in_array($ekstensi, $ekstensi_diperbolehkan) === true){
                if($ukuran < 1044070){          
                    $ngupload = move_uploaded_file($file_tmp, 'src/FileUpload/'.$nama);
                    if($ngupload){
                        echo "<script type='text/javascript'>alert('Berhasil Mengunggah');</script>";
                    }else{
                        echo "<script type='text/javascript'>alert('Gagal Mengunggah');</script>";
                    }
                }else{
                    echo "<script type='text/javascript'>alert('Ukuran File terlalu besar');</script>";
                }
            }else{
                echo "<script type='text/javascript'>alert('Ekstensi File Tidak Diperbolehkan');</script>";
            }
        }

?>