Just between us, dumping diesel in a tank destined for a gasoline engine does little real harm, it likely won't run real smooth and it will smell a bit odd and it may even not run at all but the diesel does no permanent mechanical damage to a gasoline engine.
Diesel is basically very low octane gasoline.
No, a gasoline engine can't and won't run on straight diesel.
But the oily fuel does no actual harm to the engine.
All right, it might foul a plug or three.
It can appear to the inexperienced driver that serious harm has occured.
But it has not.
The inexperienced driver may end up with a large repair bill, too.
But that is nobody's fault but theirs.
If a gasoline tank is full of diesel, draining it is the only option.
It's not hard to do, annoying, time consuming, but not hard.
If they didn't put that much in, adding super unleaded to the F mark fixes it.
So, mixing diesel where there should be gasoline, good for some laughs, no harm done.
Now, putting gasoline through a diesel engine is a different story.