make the build fail if nwjs binary isn't successfully downloaded

l2ork_addons/tar_em_up.sh

@@ -142,7 +142,7 @@ if [ ! -d "../pd/nw/nw" ]; then
 	nwjs_url=${nwjs_url}/$nwjs_filename
 	echo "Fetching the nwjs binary from"
 	echo "$nwjs_url"
-	wget -nv $nwjs_url
+        wget -nv $nwjs_url || exit 1
 	if [[ $os == "win" || $os == "osx" ]]; then
 		unzip $nwjs_filename
 	else