fix: Always expand folders when adding a sub-folder, b=no-bug, c=folders

src/zen/folders/ZenFolder.mjs

@@ -149,6 +149,12 @@
     }
 
     createSubfolder() {
+      // We need to expand all parent folders
+      let currentFolder = this;
+      do {
+        currentFolder.collapsed = false;
+        currentFolder = currentFolder.group;
+      } while (currentFolder);
       gZenFolders.createFolder([], {
         renameFolder: !gZenUIManager.testingEnabled,
         label: 'Subfolder',

src/zen/folders/ZenFolders.mjs

@@ -1059,9 +1059,7 @@
           // We don't need to do anything if the URL is invalid. e.g. about:blank
         }
         let tabLabel = tab.label || '';
-        let iconURL =
-          gBrowser.getIcon(tab) ||
-          "data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='100' height='100'%3E%3C/svg%3E";
+        let iconURL = gBrowser.getIcon(tab) || PlacesUtils.favicons.defaultFavicon;
 
         icon.src = iconURL;