Fix segfault when the Wizard tried teleporting on the planes

The wizard of Yendor tried teleporting to the stairs on the
plane of Earth, but there are none there.

This was caused by the stairs structure reworking.

Fixes #422

diff --git a/src/teleport.c b/src/teleport.c
index e5e34c5ae145d033605fc077f3907f3fbb25efa1..5c7b84964d94c757b0125b585b2b26a50a6bb4d4 100644 (file)
--- a/src/teleport.c
+++ b/src/teleport.c
@@ -1284,7 +1284,6 @@ struct monst *mtmp; /* mx==0 implies migrating monster arrival */
 boolean suppress_impossible;
 {
     register int x, y, trycount;
-    stairway *stway;
 
     if (mtmp == u.usteed) {
         tele();
@@ -1292,19 +1291,19 @@ boolean suppress_impossible;
     }
 
     if (mtmp->iswiz && mtmp->mx) { /* Wizard, not just arriving */
+        stairway *stway;
+
         if (!In_W_tower(u.ux, u.uy, &u.uz)) {
             stway = stairway_find_forwiz(FALSE, TRUE);
-            x = stway->sx;
-            y = stway->sy;
         } else if (!stairway_find_forwiz(TRUE, FALSE)) { /* bottom level of tower */
             stway = stairway_find_forwiz(TRUE, TRUE);
-            x = stway->sx;
-            y = stway->sy;
         } else {
             stway = stairway_find_forwiz(TRUE, FALSE);
-            x = stway->sx;
-            y = stway->sy;
         }
+
+        x = stway ? stway->sx : 0;
+        y = stway ? stway->sy : 0;
+
         /* if the wiz teleports away to heal, try the up staircase,
            to block the player's escaping before he's healed
            (deliberately use `goodpos' rather than `rloc_pos_ok' here) */