fixed a core dump

client.c

@@ -52,7 +52,6 @@ focus(Client *c)
 	if (!issel)
 		return;
 	Client *old = sel;
-	XEvent ev;
 
 	sel = c;
 	if(old && old != c)

tag.c

@@ -211,8 +211,10 @@ restack()
 			else
 				m++;
 		}
-
-	n = 2 * (f + m);
+	if(!(n = 2 * (f + m))) {
+		drawstatus();
+		return;
+	}
 	if(nwins < n) {
 		nwins = n;
 		wins = erealloc(wins, nwins * sizeof(Window));