LandingGadget: Fix Case when there is only one file in the zip

gadget/gadget_landing_cribjs.js

@@ -12,13 +12,13 @@
     zip.forEach(function (relativePath, zipEntry) {
       path_list.push(relativePath);
     });
-    if (path_list) {
+    if (path_list && path_list.length > 1) {
       root_path = path_list[0].split("/")[0];
-    }
-    for (i = 0; i < path_list.length - 1; i++) {
-      if (root_path !== path_list[i].split("/")[0]) {
-        root_path = "";
-        break;
+      for (i = 0; i < path_list.length - 1; i++) {
+        if (root_path !== path_list[i].split("/")[0]) {
+          root_path = "";
+          break;
+        }
       }
     }
     if (root_path !== "" && !from_path) {