Joe,
I don't intend to do anything! Spotting the error just made me wonder what a musician should do in general if sight-reading.

As noted above, it would probably be corrected by an annotation.

I belong to the local Amateur Operatic Society, (grand name, but it is musicals they do these days - Chess was excellent) and the scores which they purchase ALWAYS have to be corrected.

What if this error occurred in an examination piece?