We had an instance where a literal semicolon was accidentally added to the top of every page on our e-commerce website. Nobody noticed it for a while because it

We had an instance where a literal semicolon was accidentally added to the top of every page on our e-commerce website. Nobody noticed it for a while because it was hidden underneath the nav bar thanks to z indexing. The weird part is that after we found it and deleted it (someone erroneously terminated a line with a semicolon in a Razor template), it crashed the site entirely. In the end, I found that the semicolon was in the <head>, and the inclusion of literal text caused document.body to be non-null. A later script in the head relied on the existence of document.body, making that particular semicolon load-bearing. (Angular 1 times, y'all.)