fix: don't create zero-width overlay for hint-less clozes

org-drill-hide-cloze-hints checked (null (match-beginning 2)) to detect
"no hint present," but the cloze regex's hint group is an empty-allowed
alternation — the group always participates in the match, so
match-beginning is always a position, never nil.

For a card like "[Paris]" (no hint), the function fell through to
org-drill-hide-region with start = end and made a zero-width overlay.
Cosmetically harmless but accumulates one stray overlay per hint-less
cloze. On a buffer with many such cards the tracking cost is real.

Switched the guard to (= (match-beginning 2) (match-end 2)) — empty match.
Found while writing tests; locked in by tests/test-org-drill-hide-show.el's
test-org-drill-hide-cloze-hints-no-hint-no-overlay.

0 files changed, 0 insertions, 0 deletions