browser.links() should return an empty list if self.page is None

[npetrangelo]

I was writing a fuzzer for a cybersecurity assignment, and it crashed when it tried to find the links on a PDF file. I think it would make more sense to return that there are no links, if the page fails to parse. This seems relatively straightforward to implement.

[hemberger]

Thanks for the suggestion! However, I think it might be misleading to have StatefulBrowser.links return an empty list if no page is currently loaded. It's a very different case than having a page with no links. Can you elaborate a bit more on the use case? Would the following be useful in your application?

links = [] if br.page is None else br.links()

At the very least, we could improve the error message when you call StatefulBrowser.links without having a page loaded.