hotfix of a serious crashing bug

.hgtags

@@ -23,3 +23,4 @@ a2c465098a3b972bbed00feda9804b6aae1e9531 2.1
 7e92f58754ae6edb3225f26d754bd89c1ff458cf 2.2
 719b37b37b0df829d7cf017ac70e353088fe5849 2.3
 32b246925086910d63147483160281a91a47479f 2.4
+dcbbfabc8ecc5f33a6cc950584de87da1a368045 2.5

config.mk

@@ -1,5 +1,5 @@
 # dwm version
-VERSION = 2.5
+VERSION = 2.5.1
 
 # Customize below to fit your system
 

tag.c

@@ -114,7 +114,8 @@ tag(Arg *arg) {
 		return;
 	for(i = 0; i < ntags; i++)
 		sel->tags[i] = (arg->i == -1) ? True : False;
-	sel->tags[arg->i] = True;
+	if(arg->i >= 0 && arg->i < ntags)
+		sel->tags[arg->i] = True;
 	arrange();
 }
 

view.c

@@ -234,7 +234,8 @@ view(Arg *arg) {
 
 	for(i = 0; i < ntags; i++)
 		seltag[i] = (arg->i == -1) ? True : False;
-	seltag[arg->i] = True;
+	if(arg->i >= 0 && arg->i < ntags)
+		seltag[arg->i] = True;
 	arrange();
 }