OH! you are so lucky that it is the non drive side... alot less money! I definitely would NOT put a tap through that crank arm in order to save it! We put way too much weight and pressure in that area, and I certainly would not trust anything to hold there. Although it's a bummer, I would definitely go to LBS and ask them to simply replace that crank arm. They come in different lengths and are shaped a bit differently(hard to explain through the computer)
so I would take the bike with you when you visit the shop. I also would have them check the driveside...it may be simply a precaution, but better there then something else happening. They also can check to see if there might be any further problems witrh the crank and bottom bracket.