vRA 8.2 - Returning helpful error message to vRA from vRO?

In 8.2 there was a bug fixed which now causes vRO to error if called with null or blank parameters are passed to an action. This is easy enough to handle by handling the null/blank value. Something like this:

if var == null or var == ""{ return ""}

Because of this I noticed the errors returned back from vRO are pretty useless. Even if you throw an exception.

My question is when you throw an exception, how can you return a helpful error message back to vRA?