REPORTER FAIL!!! -- Matthew Perry Congratulated ... For Show Being Cancelled!

File this under, "EPIC FAILURE BY A SIDELINE REPORTER!"

Here's the setup ... reporter spots Matthew Perry at the L.A. Kings game on Friday night, hours after NBC made a huge announcement about Perry's show, "Go On."

Reporter decides to CONGRATULATE Perry on the announcement, LIVE on the air.

Problem is ... the announcement was that NBC had CANCELLED the show (whoops!).

What ensues is nothing short of HILARITY.

"You know, the show that I was doing was really getting in the way of Kings games," Perry deadpanned.

Brilliant.