Add object sanity check for was_dropped/was_thrown

src/mkobj.c

@@ -2863,6 +2863,10 @@ objlist_sanity(struct obj *objlist, int wheretype, const char *mesg)
     for (obj = objlist; obj; obj = obj->nobj) {
         if (obj->where != wheretype)
             insane_object(obj, ofmt0, mesg, (struct monst *) 0);
+        if (obj->was_thrown && obj->was_dropped) {
+            insane_object(obj, "%s obj is both thrown and dropped! %s %s: %s",
+                          mesg, obj->ocarry);
+        }
         if (Has_contents(obj)) {
             if (wheretype == OBJ_ONBILL)
                 /* containers on shop bill should always be empty */