Hello everyone , I try to create new View Type (xtree)  base on Odoo document and video as below

document
https://www.odoo.com/documentation/14.0/reference/javascript_cheatsheet.html#creating-a-new-view-from-scratch

video tutorial

https://www.youtube.com/watch?v=SIoljYJhTqk

This is my module structure, I separate 4 files js instead 1 file in video

I only want to create <xtree> view and display "Hello world" in that view . But when I load module , I see this Error

Here is my code : https://github.com/luantm16110560/xtree

Please explain to me

Thanks