Note that this is not an error per se. If you don't select any revision that does not make sense and so you'll be redirected to an error page, the "return to mainpage" is meant to guide you and everything back to normalcy. There are many pages (that are not normal to come by) that have that generic return message also.

I would delete "return to [[Main Page]]" entirely. It's almost never useful.

In T251910#6501971, @Ammarpad wrote:

Note that this is not an error per se. If you don't select any revision that does not make sense and so you'll be redirected to an error page, the "return to mainpage" is meant to guide you and everything back to normalcy. There are many pages (that are not normal to come by) that have that generic return message also.

...but the actual title I'd need to return back to is even still in the visible URL!

In T251910#10584854, @ToBeFree wrote:

In T251910#6501971, @Ammarpad wrote:

Note that this is not an error per se. If you don't select any revision that does not make sense and so you'll be redirected to an error page, the "return to mainpage" is meant to guide you and everything back to normalcy. There are many pages (that are not normal to come by) that have that generic return message also.

...but the actual title I'd need to return back to is even still in the visible URL!

No, you don't actually want to return to that. It's also an error page (so you'll still see the 'return to mainpage' link there).