Oven light bulb fitting problem
The wires that support the lamp filament may be shorting out causing the breaker to trip (assuming there is no damage to the socket itself).  This can create a less than safe condition because there is a live exposed wire in the broken lamp base. If used, when the oven heats up the wire could move around and short again. If the lamp can be turned off the oven could be used. I have had success using a raw potato pressed into the broken lamp base, power off. Some times turning both clockwise then counter clockwise working both directions can loosen the lamp base so it can be removed.