correct var init

tp1/assets/data.json

@@ -110,7 +110,7 @@
       "category": "course",
       "title": "Learn Programming With JavaScript",
       "author": "Olga Volkova, Will Alexander",
-      "publisher": "OpenClatssrooms",
+      "publisher": "OpenClassrooms",
       "completion_time": "15 hours",
       "description": "This course is designed to teach you the fundamentals of the JavaScript programming language and to give you lots of practice along the way!",
       "image": "assets/images/LearnProgrammingWithJS.jpg",

tp1/lib/app_state.dart

@@ -7,22 +7,17 @@ const String filePath = '../assets/data.json';
 
 class TindBookState extends ChangeNotifier {
     String input = "";
-    late var data;
+    List<dynamic> data = <dynamic>[];
     List<int> favorites = <int>[];
 
     void loadData() async {
-        this.input = await rootBundle.loadString(filePath);
-        this.data = jsonDecode(input)['data']; 
+        input = await rootBundle.loadString(filePath);
+        data = jsonDecode(input)['data']; 
         notifyListeners();
     }
 
     Map<String, dynamic> getFav(int index) {
-        return this.data[this.favorites[index]];
-    }
-
-    void addDataToFav(Map<String, dynamic> obj){
-        favorites.add(this.data.indexOf(obj));
-        notifyListeners();
+        return data[favorites[index]];
     }
 
     void addIndexToFav(int index) {
@@ -32,7 +27,28 @@ class TindBookState extends ChangeNotifier {
         }
     }
 
+    void addDataToFav(Map<String, dynamic> obj){
+        if (! favorites.contains(data.indexOf(obj))){
+            favorites.add(data.indexOf(obj));
+            notifyListeners();
+        }
+    }
+
+    void removeIndexFromFav(int index) {
+        if (favorites.contains(index)){
+            favorites.remove(index);
+            notifyListeners();
+        }
+    }
+
+    void removeDataFromFav(Map<String, dynamic> obj){
+        if (favorites.contains(data.indexOf(obj))){
+            favorites.remove(data.indexOf(obj));
+            notifyListeners();
+        }
+    }
+
     List<String> get categories => 
             [for (Map<String, dynamic> entry in data) entry['category']];
-    Set<String> get uniqueCategories => this.categories.toSet();
+    Set<String> get uniqueCategories => categories.toSet();
 }