When element's nodetype is 9 return empty string instead of throwing error.

[8ivek]

I was constantly getting following error:
Failed to execute 'getComputedStyle' on 'Window': parameter is not of type 'Element'

and I solved it using this solution.

[aFarkas]

Thank you very much. Could you give me a test case where this problem is happening?

[8ivek]

I am getting this error in one of our private project where we are including a lot of js files, I haven't been able to isolate whats the exact case when this error is happening but I doubt this is happening when we use lazysizes.js with jquery-migrate.min.js. If i'm able to isolate i'll post it here.
Thank you!