Extracting information from PL_exception()

I'm trying to work out what information I'm able to extract from calling
PL_exception() from C after a call to PL_next_solution() has failed. I've
set up a test case in which the underlying PL predicate will hit a
guaranteed error due to it referencing another predicate that has not in
fact been defined. So PL_next_solution() fails, as expected, and
PL_exception() succeeds and returns a term_t term value. But what exactly
is the value so returned (or, rather, the structure to which it is a
handle)? I've ascertained that it is of type PL_TERM. (This is using the
latest SWI on Windows, btw.) But it isn't a list or a string, and the most
info I've been able to extract is by calling PL_get_name_arity(...), which
tells me that it has name "error" and is of arity 2. But...is that it?

In my simple console app the corresponding call sends the exception to the
console:

ERROR: test_predicate/1: Undefined procedure: nonsense_predicate/1
Exception: (6) nonsense_predicate(test_object) ?

Trying to integrate into our full-blown windows app, I don't get this kind
of error message for free. I was hoping that the exception might give it to
me, but I can't tell from the documentation whether I should expect to have
access to this message, and if so how to extract it. Any pointers would be
appreciated.

KJ
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