[force ten]

does the side indicator work when the hazard warning lights are switched on ?

the fact that you say the wing mirror indicator flashes when the car is locked and un locked suggests that the light unit is still operational for some functions so could be a wiring issue in the direction indicator circuit rather than a light strip blown or non functioning

this would require further investigation but l wouldn't be rushing to buy a replacement indicator unit

and yes a non function indicator is a fail (major)