Error 500 opening file manager on TB 1.4

[Beeta]

TB 1.4 bleeding edge (version fcf3987d011c85bb59dd7b75c9c75ef91b715036)
PHP 7.2

I'm gettin this 500 error when I try to open the file manager to upload an image:

  Error
Call to undefined function mime_content_type()
in file /home/nginx/domains/domain.com/public/adminNNNNNN/filemanager/include/php_image_magician.php at line 1745
Source file: /home/nginx/domains/domain.com/public/adminNNNNNN/filemanager/include/php_image_magician.php

1726:                } else {
1727:                    $alpha += 127 * $opacity;
1728:                }
1729:                $alphacolorxy = imagecolorallocatealpha($img, ($colorxy >> 16) & 0xFF, ($colorxy >> 8) & 0xFF, $colorxy & 0xFF, $alpha);
1730:                imagesetpixel($img, $x, $y, $alphacolorxy);
1731:            }
1732:        }
1733:    }
1734:
1735:    /**
1736:     * @param $file
1737:     * @return false|GdImage|resource
1738:     * @throws Exception
1739:     */
1740:    private function openImage($file)
1741:    {
1742:        if (!file_exists($file) && !$this->checkStringStartsWith('http://', $file) && !$this->checkStringStartsWith('https://', $file)) {
1743:            throw new Exception('Image not found.');
1744:        }
1745:        $extension = mime_content_type($file);
1746:        $extension = fix_strtolower($extension);
1747:        $extension = str_replace('image/', '', $extension);
1748:        switch ($extension) {
1749:            case 'jpg':
1750:            case 'jpeg':
1751:                $img = @imagecreatefromjpeg($file);
1752:                break;
1753:            case 'webp':
1754:                $img = @imagecreatefromwebp($file);
1755:                break;

Stack trace
1. adminNNNNNN/filemanager/include/php_image_magician.php:252 source imageLib->openImage(arguments)
2. adminNNNNNN/filemanager/include/utils.php:96 source imageLib->__construct(arguments)
3. adminNNNNNN/filemanager/dialog.php:972 source create_img_gd(arguments)

PHP version: unknown.  Code revision: unknown build for PHP unknown 

[e-com]

Misconfigured server. No fileinfo extension for PHP installed.

phpinfo();

[DRMasterChief]

same here with LiteSpeed Server and  tb 1.5.x  ,   activate the fileinfo php-extension was necessary, now the Filemanager works!