A New Jersey man was killed Thursday when the motorcycle he was riding crashed on Interstate 287 in Somerset County, authorities said. Mazen Alnaser, 28, of Whitehouse Station in Hunterdon County, was riding the motorcycle behind a vehicle in the highway’s northbound lanes when he veered to the left near milepost 16.6 in Bridgewater and hit a guardrail, according to New Jersey State Police. Alnaser was thrown from the motorcycle and struck a guardrail support post. The motorcycle continued north and struck the rear of the vehicle, police said. No other injuries were reported, and no charges we…