"...a black hole emits nothing..."

I'm under the impression that this is not exactly the case. Virtual particles can be turned into normal particles by the gravitational effects of a black hole. This is the source of Hawking radiation, which is a phenomenon that causes black holes to emit mass and energy over time and to eventually disappear.

At least this is expected. I'm not sure these effects have been experimentally demonstrated or observed yet.

Also, while not produced directly by the black hole, light is generated by matter falling into the black hole being compressed and subject to friction before it actually crosses the event horizon.