While preparing a PR, if I toggle 'Ignore Whitespace' the page reloads without warning me that I will lose unsaved changes

I wanted to see what my PR would look like if I ignored whitespace (so I could decide whether I should bother advising my reviewers to do so), but when I clicked it the page automatically reloaded and I lost all of what I wrote in the PR description. This is a really annoying, but trivial UX bug.