The Browser component executes an asynchronous filesystem read in its componentDidMount method. This operation (or any other asynchronous operation) breaks the Istanbul code coverage produced by Jest and can't be ignored using any flavor of ignore syntax. If this single statement is commented out manually, 100% code coverage is achieved, hinting at a transpilation error.

Ideally, we should find a way to ignore this line or work around this issue to achieve 100% coverage.