Running test out of the box results in error

[Jahvy]

Running the test after cloning the repo resulted in the error below. I came across a similar issue in my own React implementation for surveyjs, and I was wondering if someone has any advice on how to tackle this.

[tsv2013]

Please check the source code of the findSheet function:

https://github.com/surveyjs/surveyjs/blob/master/src/stylesmanager.ts#L350-L357

It operates with real DOM elements. That's why I think it fails in the unit tests.