Expected culprit format with browser SDK?

I’m trying out the browser SDK and have manually trigged an error using the following:

throw new Error('Something really, really bad happened here!');

This creates an issue on Sentry as expected with the correct source and everything, I’m just not so sure about the format of the “culprit” string as seen at the top of the attached screenshot:

Screenshot 2020-10-18 015032

Is this the expected format of this? Then why the question mark and parentheses? And why does the path not contain a file extension?