I followed this tutorial https://www.oocademy.com/v13.0/tutorial/creating-and-using-javascript-assets-in-odoo-54

but am going this error when resizing my screen

in the console:  TypeError: undefined is not an object (evaluating 'el.getBoundingClientRect')

and this in odoo 

TypeError: undefined is not an object (evaluating 'el.getBoundingClientRect')

https://hesaby-hesaby-dev-l-1284261.dev.odoo.com/web/static/src/js/core/dom.js:554
Traceback:
computeFloatOuterWidthWithMargins@https://hesaby-hesaby-dev-l-1284261.dev.odoo.com/web/static/src/js/core/dom.js:554:26
_adapt@https://hesaby-hesaby-dev-l-1284261.dev.odoo.com/web/static/src/js/core/dom.js:543:68
later@https://hesaby-hesaby-dev-l-1284261.dev.odoo.com/web/static/lib/underscore/underscore.js:821:30