Error when adding video to "My List"

*I'm submitting a ...*
- [ x] bug report
- [ ] feature request
- [ ] support request

## General infomration

### Prerequisites

* [x ] Are you running the latest version?

### Description

When selecting a video and adding to My List, an error message pops up.

### Steps to Reproduce

1. Select Video
2. Add to My List

**Expected behavior:** [What you expected to happen]
Video would be added to My List in Netflix
**Actual behavior:** [What actually happened]
Error message and video is not added to My List in Netflix
## Context (Environment)

### Installation

* [x ] I installed the plugin via zip from the Releases page
* [x ] I´m using the Netflix Repo
* [ ] I´m using a different source (Please tell which)

### Operating System

* [ x] Linux (x86/x64)
* [ ] OSX (x86/x64)
* [ ] Windows (x86/x64)
* [ ] Linux (ARM)
* [ ] Android

#### Additional informatin on the environment

Arch based Linux with Kodi 18 alpha 1

## Debug log

https://pastebin.com/0dD8AdJN

Start by reproducing the My List action in Kodi 18 on Arch-based Linux, then inspect the linked debug log at pastebin.com/0dD8AdJN to identify the failing entry point. Done means selecting a video adds it to Netflix My List without showing an error.

Written by the indexing model from the issue text.