Fix hang test on Promise ~~ Enum
Fix hang test on Promise ~~ Enum

We don't throw in smartmatches, as test expect. Test for value instead
of expecting exception. This still tests for the hang, which was the
original purpose of the test.

The test was added[^1] 8 months ago and isn't part of 6.c language.

[1] https://github.com/perl6/roast/commit/70aa3cf924985735e09d

bitrauser/roast,bitrauser/roast,dogbert17/roast,perl6/roast,dogbert17/roast