Unable to link to the raw markup of this forum post

Easier is to middle-click or otherwise open the link in a new tab/window. It does require that the person clicking the link know to do that, though. You can also reload the page and have it work.

It’s a known problem, and low priority:

https://meta.discourse.org/t/bug-raw-links-generate-error-and-require-reloading/44084