I popped into a garage and they thought it should have cut it out, they said 3-4 litres of diesel in a 1/4 tank of unleaded should have been smokey but still run. The engine management light is on, is this normal if the car cuts out because of wrong fuel?

Wondering if it's something else and just a coincidence.

The fuel in it that i've managed to drain from the pump doesn't smell very strong, makes me think it is diesel