ui: Intermediate page with error message always loads first when going to range debug page

[a-robinson]

On indigo, whenever I try to load a range debug page by changing the range ID in the URL and reloading the page, it always flashes this error page on the screen for about a second before redirecting to the actual page:

Intermediate page:

End page:

This happens every time when I switch back and forth between the page for range 15 and the page for range 16

[a-robinson]

And for what it's worth, indigo is currently running aec9e34 plus #17733.

[BramGruneir]

Sounds like we're handling a case of still loading as an error, I'll take a look.