It would be nice if division by zero was in here, but I think throwing an exception would be bad.

The div-by-zero check is in intepreter.cpp so in theory a zero should never be passed to this function. But that doesn't preclude the possibility of a future op code calling the div operator without a zero check. Given that in theory the exception would never be triggered unless someone makes a mistake in the future would an exception here to act as a guard be a problem? I don't know if C++ has the concept of checked and unchecked exceptions but if so I would suggest an unchecked exception.

Whatever happens here should happen to the mod operator as well.

Oops I had it backwards, the below operator actually calls this one. Nevermind!

An exception could be equally as bad. Is an std::optional or std::variant a reasonable possibility?

Paging @deadalnix for an opinion.

Gentle repaging @deadalnix for an opinion on whether and how to add another level of checking for div by zero here, in case the operator is used by some other code in the future.

There was an open question here about whether to add an additional check for division by zero. In the current implementation, this is checked before this operator is used, however this cannot be guaranteed for future uses of this operator. For previous inline comments, see https://reviews.bitcoinabc.org/D1093?id=2897

I spoke with deadalnix on this. It should not be necessary. Any exception would be inappropriate anyways. I think just having a test for this case is sufficient.