union: fix off-by-one in choose operator
union: fix off-by-one in choose operator

Fix off-by-one bounds check when instantiating the choose operator.

Signed-off-by: Helge Bahmann <c5618920f622561f9c0ec5c42219c4c08180149f@chaoticmind.net>

phate/jive,phate/jive,phate/jive