Failed to construct 'CustomElement' error when using with Flow

[TatuLund]

I tried to integrated this web component with Flow, but I am getting this error

"NotSupportedError: Failed to construct 'CustomElement': The result must not have attributes"

See also: https://stackoverflow.com/questions/43836886/failed-to-construct-customelement-error-when-javascript-file-is-placed-in-head