improved handling of absent or loading icons

app/lib/features/geckoview/features/browser/presentation/widgets/tab_icon.dart

@@ -18,7 +18,9 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 import 'package:flutter/material.dart';
+import 'package:flutter_material_design_icons/flutter_material_design_icons.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:nullability/nullability.dart';
 import 'package:skeletonizer/skeletonizer.dart';
 import 'package:weblibre/domain/services/generic_website.dart';
 import 'package:weblibre/features/geckoview/domain/entities/states/tab.dart';
@@ -46,12 +48,16 @@ class TabIcon extends HookConsumerWidget {
     }, [state.icon, state.url]);
 
     return Skeletonizer(
-      enabled:
-          icon.connectionState != ConnectionState.done && icon.data == null,
+      enabled: icon.connectionState != ConnectionState.done,
       child: Skeleton.replace(
         replacement: Bone.icon(size: iconSize),
         child: RepaintBoundary(
-          child: RawImage(image: icon.data, height: iconSize, width: iconSize),
+          child:
+              icon.data.mapNotNull(
+                (icon) =>
+                    RawImage(image: icon, height: iconSize, width: iconSize),
+              ) ??
+              Icon(MdiIcons.web, size: iconSize),
         ),
       ),
     );

app/lib/features/geckoview/features/search/presentation/widgets/search_modules/history_suggestions.dart

@@ -20,6 +20,7 @@
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_hooks/flutter_hooks.dart';
+import 'package:flutter_material_design_icons/flutter_material_design_icons.dart';
 import 'package:go_router/go_router.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:nullability/nullability.dart';
@@ -91,11 +92,15 @@ class HistorySuggestions extends HookConsumerWidget {
 
                       return ListTile(
                         leading: RepaintBoundary(
-                          child: RawImage(
-                            image: icon.data?.value,
-                            height: 24,
-                            width: 24,
-                          ),
+                          child:
+                              icon.data?.value.mapNotNull(
+                                (favicon) => RawImage(
+                                  image: favicon,
+                                  height: 24,
+                                  width: 24,
+                                ),
+                              ) ??
+                              const Icon(MdiIcons.web, size: 24),
                         ),
                         title: suggestion.title.mapNotNull(
                           (title) => Text(title),

app/lib/presentation/widgets/url_icon.dart

@@ -40,7 +40,7 @@ class UrlIcon extends HookConsumerWidget {
     );
 
     return Skeletonizer(
-      enabled: !icon.hasData,
+      enabled: icon.connectionState != ConnectionState.done,
       child: SizedBox.square(
         dimension: iconSize,
         child: (icon.data != null)

app/lib/presentation/widgets/website_title_tile.dart

@@ -18,6 +18,7 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 import 'package:flutter/material.dart';
+import 'package:flutter_material_design_icons/flutter_material_design_icons.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:nullability/nullability.dart';
 import 'package:skeletonizer/skeletonizer.dart';
@@ -40,10 +41,16 @@ class WebsiteTitleTile extends HookConsumerWidget {
         skipLoadingOnReload: true,
         data: (info) {
           return ListTile(
-            leading: RawImage(
-              image: info.favicon?.image.value,
-              height: 24,
-              width: 24,
+            leading: RepaintBoundary(
+              child:
+                  info.favicon.mapNotNull(
+                    (favicon) => RawImage(
+                      image: favicon.image.value,
+                      height: 24,
+                      width: 24,
+                    ),
+                  ) ??
+                  const Icon(MdiIcons.web, size: 24),
             ),
             contentPadding: EdgeInsets.zero,
             title: Text(