do not print <math class="eqn"><mrow></mrow></math> for empty .EQ;

issue reported by bentley@

1 files changed, 3 insertions, 0 deletions

diff --git a/eqn_html.c b/eqn_html.c
index a56c6891..c8d5b6f7 100644
--- a/eqn_html.c
+++ b/eqn_html.c
@@ -231,6 +231,9 @@ print_eqn(struct html *p, const struct eqn_box *bp)
 {
 	struct tag	*t;
 
+	if (bp->first == NULL)
+		return;
+
 	t = print_otag(p, TAG_MATH, "c", "eqn");
 
 	p->flags |= HTML_NONOSPACE;