Handle declaration issue related to excplicit download percentage pro…

…gress tracking.

context/scripts/Web.cs

@@ -200,6 +200,7 @@ private static async Task<bool> DownloadFile(string name, string sourceUrl, stri
             {
                 Stopwatch stopwatch = new Stopwatch();
                 stopwatch.Start();
+                long lastPercent = -1;
                 client.DownloadProgressChanged += (sender, args) =>
                     {
                         long percent = 100 * args.BytesReceived / args.TotalBytesToReceive;