Here is my function that I've isolated the issue too which is failing with a 500 error in the console: What am I doing incorrectly/missing here?
.../  
 private function addSettings($username, $settings) 
  {
    $sql = "INSERT INTO APP.USERDB(userid,obj_json) VALUES(:userid,:obj_json)";
    $stmt = oci_parse($this->db, $sql);
    $stmt->oci_bind_by_name(':userid', $username);
    $stmt->oci_bind_by_name(':obj_json', $settings);
    return $stmt->execute();
    if(isset($_POST['obj_json']) && !empty($_POST['obj_json'])) {
        $settings = $_POST['obj_json'];
        $prefs = new UserSettingsRepository;
        $response = $prefs->addSettings($username, $settings);
        echo 'ok';
    }
  }
.../
