feat: Fix framework assertion when adding an item

lib/main.dart

@@ -122,9 +122,13 @@ class MyApp extends StatelessWidget {
         if (state is NoopNavigationState) {
           // NOOP
         } else if (state is PushNavigationState) {
-          _router.go(state.destination);
-        } else if (state is GoNavigationState) {
           _router.push(state.destination);
+        } else if (state is GoNavigationState) {
+          if (_router.canPop()) {
+            _router.replace(state.destination);
+          } else {
+            _router.go(state.destination);
+          }
         } else if (state is PoppedNavigationState) {
           _router.pop();
         }

lib/src/ui/widgets/image.dart

@@ -4,7 +4,7 @@ import 'package:flutter/material.dart';
 class AnimeCoverImage extends StatelessWidget {
   const AnimeCoverImage({
     required this.url,
-    required this.hero,
+    this.hero,
     this.cached = true,
     this.extra,
     this.onTap,
@@ -18,7 +18,7 @@ class AnimeCoverImage extends StatelessWidget {
   final bool cached;
 
   /// The hero tag of the image.
-  final String hero;
+  final String? hero;
 
   /// An extra widget with a translucent backdrop.
   final Widget? extra;
@@ -28,53 +28,59 @@ class AnimeCoverImage extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return Hero(
-      tag: hero,
-      child: ClipRRect(
-        borderRadius: BorderRadius.circular(8),
-        child: Material(
-          child: SizedBox(
-            height: 100 * (16 / 9),
-            width: 120,
-            child: InkWell(
-              onTap: onTap ?? () {},
-              child: Stack(
-                children: [
-                  Positioned(
-                    left: 0,
-                    right: 0,
-                    top: 0,
-                    bottom: 0,
-                    child: DecoratedBox(
-                      decoration: BoxDecoration(
-                        image: DecorationImage(
-                          image: cached
-                              ? CachedNetworkImageProvider(url) as ImageProvider
-                              : NetworkImage(url),
-                          fit: BoxFit.cover,
-                        ),
+    final image = ClipRRect(
+      borderRadius: BorderRadius.circular(8),
+      child: Material(
+        child: SizedBox(
+          height: 100 * (16 / 9),
+          width: 120,
+          child: InkWell(
+            onTap: onTap ?? () {},
+            child: Stack(
+              children: [
+                Positioned(
+                  left: 0,
+                  right: 0,
+                  top: 0,
+                  bottom: 0,
+                  child: DecoratedBox(
+                    decoration: BoxDecoration(
+                      image: DecorationImage(
+                        image: cached
+                            ? CachedNetworkImageProvider(url) as ImageProvider
+                            : NetworkImage(url),
+                        fit: BoxFit.cover,
                       ),
                     ),
                   ),
-                  if (extra != null)
-                    Positioned(
-                      left: 0,
-                      bottom: 0,
-                      right: 0,
-                      child: SizedBox(
-                        height: 40,
-                        child: ColoredBox(
-                          color: Colors.black54,
-                          child: extra,
-                        ),
+                ),
+                if (extra != null)
+                  Positioned(
+                    left: 0,
+                    bottom: 0,
+                    right: 0,
+                    child: SizedBox(
+                      height: 40,
+                      child: ColoredBox(
+                        color: Colors.black54,
+                        child: extra,
                       ),
                     ),
-                ],
-              ),
+                  ),
+              ],
             ),
           ),
         ),
       ),
     );
+
+    if (hero != null) {
+      return Hero(
+        tag: hero!,
+        child: image,
+      );
+    }
+
+    return image;
   }
 }

lib/src/ui/widgets/list_item.dart

@@ -76,8 +76,6 @@ class ListItem extends StatelessWidget {
           children: [
             AnimeCoverImage(
               cached: cached,
-              // TODO(Unknown): Have the ID here
-              hero: thumbnailUrl,
               extra: imageExtra,
               url: thumbnailUrl,
             ),