First is a vane switch, which senses the airflow being generated and closes a switch when adequate flow is reached. If flow diminishes, it springs open. You may need a relay to control the lamp, or run a trip circuit.
Second is a rotation sensor on the fan motor. Most DC brushless fans have a sensor, some with a sense line out, or easily added. That feeds signal to a timer circuit that the rotation sensor keeps at bay. If the rotation slows down or stop, it trips the timer, which trips the lamp off.
Third is a thermal sensor fixed to the lamp electronics or housing, chosen of configured so that an overheat opens current to the lamp or its control circuit.