A bullet piercing the skin of a pressurized airliner would most likely not be a big deal. They are designed for it believe it or not. The skin is designed to be "ripstop" so that you might have a partial or complete depressurization which is actually no big deal, and in this circumstance would even be working in the crews favor, but beyond that, nothing is likely to happen.
Several large jets were hit by gunfire during the Los Angeles Rodney king riots. They all landed safely.
A taser discharge INSIDE the aircraft however, I am nowhere near as sure about. A lightning strike is designed to be whicked off the outside of the aircraft. A taser inbedding itself in the cicuit breaker pannels on the other hand is a completely different animal.
So on the balance, an aircraft is actually designed to take the sort of damage a bullet would inflict, I do not believe anythought has been given to a taser however.
Bohica