Fix variable declaration in update detection

Author: Bentroen

scripts/check_updates/check_updates.gml

@@ -35,9 +35,9 @@ function check_updates() {
 			    var res = async_load[? "result"];
 				res = json_parse(res);
 
+				var release = -1;
 				if (check_prerelease) {
 					// Iterate array of releases and get the first (latest) release OR pre-release
-					var release = -1;
 					for (var i = 0; i < array_length(res); i++) {
 						if (check_prerelease || !res[i].prerelease) {
 							release = res[i];