Fix bug 1416 (but expose bug 1417).

diff --git a/lib/dotgen/mincross.c b/lib/dotgen/mincross.c
index c21fac39995815b9df7ed3ba3e92ce435a090c19..0cec68e61bda61574710c20839c3a4f75db555e1 100644 (file)
--- a/lib/dotgen/mincross.c
+++ b/lib/dotgen/mincross.c
@@ -695,7 +695,8 @@ void flat_rev(Agraph_t * g, Agedge_t * e)
     int j;
     Agedge_t *rev;
 
-    for (j = 0; (rev = ND_flat_out(e->head).list[j]); j++)
+    if (!ND_flat_out(e->head).list) rev = NULL;
+    else for (j = 0; (rev = ND_flat_out(e->head).list[j]); j++)
        if (rev->head == e->tail)
            break;
     if (rev) {