Unexpected error: `pow` with non-numeric args

[helins]

Calling pow with a non-numeric argument results in a fatal error and breaks the executing account.

Cause: the Core class do not check if arguments are numbers for graceful failure while the RT class does and throws an IllegalArgumentException.

[mikera]

Thanks!

Fixed this specific case. Might need to experiment a bit more to see if there are any other edge cases here.

[helins]

Unfortunately results in a different kind of fatal error in the current online version:

It might be best that we collect that sort of errors with generative testing and consider them later. I would be easier to see common ground between some of them, deeper issues.

[helins]

Looks fully fixed in my gen tests.