More bug fixes (see description)

- Fixed bug where opening room would show null-error,
  for a couple of seconds.
  This was caused by the FAB not checking if widget.info!=null

- Added try&catch for item category,
  to prevent index-out-of-bounds when the item uses a category
  that no longer exists

- Renamed add/remove Articles to fit the new name: ShoppingListItem

lib/backend/permissions.dart

@@ -62,11 +62,11 @@ class ServerPermission {
 }
 
 class RoomPermission {
-  static int get addArticles {
+  static int get addShoppingListItems {
     return oB("0000001");
   }
 
-  static int get removeArticles {
+  static int get removeShoppingListItems {
     return oB("0000010");
   }
 
@@ -92,8 +92,8 @@ class RoomPermission {
 
   static List<int> get asList {
     return [
-      addArticles,
-      removeArticles,
+      addShoppingListItems,
+      removeShoppingListItems,
       editRoomContent,
       changeMeta,
       ota,

lib/backend/request.dart

@@ -31,6 +31,7 @@ Future<Response> postWithCreadentials(
     required User credentials}) async {
   Map<String, String> headers = {
     "Content-Type": "application/json",
+    'Connection': 'keep-alive',
     'Authorization':
     'Digest name=${credentials.username} server=${target.tag} accountKey=${credentials.password}'
   };

lib/screens/room/pages/categories.dart

@@ -178,6 +178,7 @@ class _RoomCategoriesPageState extends State<RoomCategoriesPage> {
                                         credentials: user),
                                       onOK: (_) async {
                                         // TODO: remove cached category
+                                        fetchCategories();
                                       },
                                       after: () {
                                         // close popup
@@ -232,10 +233,10 @@ class _RoomCategoriesPageState extends State<RoomCategoriesPage> {
           });
         },
       ),
-      floatingActionButton: ((widget.info?.isAdmin ?? false) ||
+      floatingActionButton: (widget.info != null && ((widget.info?.isAdmin ?? false) ||
         (widget.info?.isOwner ?? false) ||
         ((widget.info?.permissions)! & RoomPermission.editRoomContent !=
-          0))
+          0)))
       ? FloatingActionButton.extended(
         icon: const Icon(Icons.add),
         label: Text(AppLocalizations.of(context)!.newCategoryShort),

lib/screens/room/pages/list.dart

@@ -200,12 +200,15 @@ class _ShoppingListPageState extends State<ShoppingListPage> {
             itemBuilder: (context, index) {
               final item = list[index];
 
+              RoomCategory cat = RoomCategory.other(context);
+              try {
+                cat = categories[item.category!];
+              }catch(_){}
+
               return ShoppingListItem(
                 name: item.name,
                 description: item.description,
-                category: (item.category != null)
-                ? categories[item.category!]
-                : RoomCategory.other(context),
+                category: cat,
                 key: Key(item.id.toString()),
                 inCart: item.state != 0,
                 onDismiss: () {
@@ -294,10 +297,12 @@ class _ShoppingListPageState extends State<ShoppingListPage> {
             },
           )
       ]),
-      floatingActionButton: ((widget.info?.isAdmin ?? false) ||
-        (widget.info?.isOwner ?? false) ||
-        ((widget.info?.permissions)! & RoomPermission.editRoomContent !=
-          0))
+      floatingActionButton: (widget.info != null &&
+        ((widget.info?.isAdmin ?? false) ||
+          (widget.info?.isOwner ?? false) ||
+          ((widget.info?.permissions)! &
+            RoomPermission.addShoppingListItems !=
+            0)))
       ? FloatingActionButton.extended(
         icon: const Icon(Icons.add),
         label: Text(AppLocalizations.of(context)!.newItemShort),

lib/screens/room/pages/products.dart

@@ -81,10 +81,10 @@ class _RoomProductsPageState extends State<RoomProductsPage> {
           );
         },
       ),
-      floatingActionButton: ((widget.info?.isAdmin ?? false) ||
+      floatingActionButton: (widget.info != null && ((widget.info?.isAdmin ?? false) ||
         (widget.info?.isOwner ?? false) ||
         ((widget.info?.permissions)! & RoomPermission.editRoomContent !=
-          0))
+          0)))
       ? FloatingActionButton.extended(
         icon: const Icon(Icons.add),
         label: Text(AppLocalizations.of(context)!.newProductShort),