Erreur fatale inexpliquée

<?php
if(isset($_POST['file']) and isset($_POST['file_data']))
{
    function decode_chunk($data) {

        global $mime;
    
        $data = explode(';base64,', $data);
        $mime = explode('data:', $data[0])[1];

        if (!is_array($data) || !isset($data[1])) {
            return false;
        }

        $data = base64_decode($data[1]);
        if (!$data) {
            return false;
        }

        return $data;
    }

        $file_data = decode_chunk($_POST['file_data']);

        if (false === $file_data) {
            echo "error";
        }

        $dbh = new PDO('mysql:host=localhost;dbname=db0001', 'root', '', array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION));
        $stmt = $dbh->prepare("insert into files-v2 values(0,?,?,?)");
        $stmt->bindParam(1,$_POST['file']);
        $stmt->bindParam(2,$mime);
        $stmt->bindParam(3,$file_data);
        $stmt->execute();

        echo json_encode([]);
    }