Fix hidden error if request was never even started

If a HTTP request failed to even connect, then the logic determining
whether to retry a partial download would inadvertently throw an error
before it could re-throw the causing error, which resulted in a
confusing error dialog.

launcher/src/main/java/com/skcraft/launcher/install/HttpDownloader.java

@@ -269,7 +269,7 @@ public class HttpDownloader implements Downloader {
 
                 // We only want to try to resume a partial download if the request succeeded before
                 // throwing an exception halfway through. If it didn't succeed, just throw the error.
-                if (tries >= tryCount || !request.isSuccessCode()) {
+                if (tries >= tryCount || !request.isConnected() || !request.isSuccessCode()) {
                     throw e;
                 }
 

launcher/src/main/java/com/skcraft/launcher/util/HttpRequest.java

@@ -265,6 +265,15 @@ public class HttpRequest implements Closeable, ProgressObservable {
         return inputStream;
     }
 
+    /**
+     * Check if a connection was ever made
+     *
+     * @return True if a connection is available, false otherwise
+     */
+    public boolean isConnected() {
+        return conn != null;
+    }
+
     /**
      * Buffer the returned response.
      *