Sorry to say this, but the surprising thing is that this has not happened before.
i would bet the dash 8 was departing on 14 and the c172 was doing touch and goes on 07. ATC routinely allow the situation in which a training a/c doing circuits on 07, flies over the top of departing a/c. It’s always made me uncomfortable. All they have to do is hold the departing a/c for 30 seconds longer.
could have been much worse.