Added ability to replace JsonView with Error widget

example/lib/examples/github_user.dart

@@ -18,7 +18,10 @@ class JsonViewApp extends StatelessWidget {
         appBar: AppBar(title: Text('flutter_json_view 1.1.2')),
         body: Padding(
           padding: const EdgeInsets.all(10),
-          child: JsonView.asset('assets/github_user.json'),
+          child: JsonView.asset(
+            'assets/github_user.json',
+            onError: const Text("Failed to load Asset"),
+          ),
         ),
       ),
     );

example/lib/examples/green_custom.dart

@@ -89,6 +89,7 @@ class JsonViewApp extends StatelessWidget {
                 ),
               ),
             ),
+            onError: const Text("Failed to parse String"),
           ),
         ),
       ),

example/lib/examples/map.dart

@@ -29,6 +29,7 @@ class JsonViewApp extends StatelessWidget {
                 'height': 186.5
               },
             },
+            onError: Text("Failed to parse map"),
           ),
         ),
       ),

example/lib/examples/pink.dart

@@ -36,6 +36,7 @@ class JsonViewApp extends StatelessWidget {
                 color: Colors.purple,
               ),
             ),
+            onError: const Text("Failed to parse String"),
           ),
         ),
       ),

example/lib/main.dart

@@ -45,13 +45,15 @@ class _HomeScreenState extends State<_HomeScreen> {
               JsonView.string(
                 '{"author":{"name": "Stas", "lastName": "Ilin", "githubLogin": "Frezyx", "age": 19, "man": true, "height": 186.5}}',
                 theme: const JsonViewTheme(viewType: JsonViewType.collapsible),
+                onError: const Text("Failed to parse String"),
               ),
               const SizedBox(height: 10),
               Text('Base', style: theme.textTheme.headlineSmall),
               const SizedBox(height: 2),
               JsonView.string(
                 '{"author":{"name": "Stas", "lastName": "Ilin", "githubLogin": "Frezyx", "age": 19, "man": true, "height": 186.5}}',
                 theme: const JsonViewTheme(viewType: JsonViewType.base),
+                onError: const Text("Failed to parse String"),
               ),
               const SizedBox(height: 10),
               Text('Big data', style: theme.textTheme.headlineSmall),
@@ -62,6 +64,7 @@ class _HomeScreenState extends State<_HomeScreen> {
                   'assets/github_user.json',
                   theme:
                       const JsonViewTheme(viewType: JsonViewType.collapsible),
+                  onError: const Text("Failed to parse JSON"),
                 ),
               ),
             ],

lib/src/builders/asset_json_view_builder.dart

@@ -5,16 +5,18 @@ import 'package:flutter_json_view/src/widgets/widgets.dart';
 import 'builders.dart';
 
 class AssetJsonViewBuilder implements JsonViewBuilder {
-  AssetJsonViewBuilder(this.path, {JsonViewTheme? jsonViewTheme})
+  AssetJsonViewBuilder(this.path, this.onError, {JsonViewTheme? jsonViewTheme})
       : _jsonViewTheme = jsonViewTheme ?? const JsonViewTheme();
 
   final String path;
+  final dynamic onError;
   final JsonViewTheme _jsonViewTheme;
 
   @override
   Widget build() {
     return JsonLoaderItem(
       path: path,
+      onError: onError,
       jsonViewTheme: _jsonViewTheme,
     );
   }

lib/src/builders/common_json_view_builder.dart

@@ -10,6 +10,7 @@ class CommonJsonViewBuilder implements JsonViewBuilder {
       : _jsonViewTheme = jsonViewTheme;
 
   final dynamic jsonObj;
+
   final JsonViewTheme _jsonViewTheme;
 
   @override
@@ -31,7 +32,10 @@ class CommonJsonViewBuilder implements JsonViewBuilder {
         jsonObj: jsonObj as List,
         jsonViewTheme: _jsonViewTheme,
       );
+    } else if (jsonObj is Widget) {
+      return jsonObj;
     }
+    ;
     return PrimitiveBuilder(
       jsonObj,
       jsonViewTheme: _jsonViewTheme,

lib/src/builders/map_json_view_builder.dart

@@ -4,13 +4,14 @@ import 'package:flutter_json_view/src/theme/json_view_theme.dart';
 import 'builders.dart';
 
 class MapJsonViewBuilder implements JsonViewBuilder {
-  MapJsonViewBuilder(this.map, {JsonViewTheme? jsonViewTheme})
+  MapJsonViewBuilder(this.map, this.onError, {JsonViewTheme? jsonViewTheme})
       : _commonBuilder = CommonJsonViewBuilder(
           map,
           jsonViewTheme: jsonViewTheme ?? const JsonViewTheme(),
         );
 
   final Map<String, dynamic> map;
+  final dynamic onError;
   final JsonViewBuilder _commonBuilder;
 
   @override

lib/src/builders/string_json_view_builder.dart

@@ -5,13 +5,15 @@ import 'package:flutter_json_view/src/utils/utils.dart';
 import 'builders.dart';
 
 class StringJsonViewBuilder implements JsonViewBuilder {
-  StringJsonViewBuilder(this.jsonString, {JsonViewTheme? jsonViewTheme})
+  StringJsonViewBuilder(this.jsonString, this.onError,
+      {JsonViewTheme? jsonViewTheme})
       : _commonBuilder = CommonJsonViewBuilder(
-          JsonConverter.jsonStringToObject(jsonString),
+          JsonConverter.jsonStringToObject(jsonString, onError),
           jsonViewTheme: jsonViewTheme ?? const JsonViewTheme(),
         );
 
   final String jsonString;
+  final dynamic onError;
   final JsonViewBuilder _commonBuilder;
 
   @override

lib/src/flutter_json_view.dart

@@ -14,12 +14,15 @@ class JsonView extends StatefulWidget {
   JsonView.string(
     String jsonString, {
     Key? key,
+    required Widget onError,
     JsonViewTheme? theme,
   })  : _stringData = jsonString,
         _mapData = null,
         _assetsPath = null,
+        _onError = onError,
         _builder = StringJsonViewBuilder(
           jsonString,
+          onError,
           jsonViewTheme: theme,
         ),
         super(key: key);
@@ -32,12 +35,15 @@ class JsonView extends StatefulWidget {
   JsonView.asset(
     String path, {
     Key? key,
+    required Widget onError,
     JsonViewTheme? theme,
   })  : _assetsPath = path,
         _mapData = null,
         _stringData = null,
+        _onError = onError,
         _builder = AssetJsonViewBuilder(
           path,
+          onError,
           jsonViewTheme: theme,
         ),
         super(key: key);
@@ -47,19 +53,23 @@ class JsonView extends StatefulWidget {
   JsonView.map(
     Map<String, dynamic> map, {
     Key? key,
+    required Widget onError,
     JsonViewTheme? theme,
   })  : _mapData = map,
         _stringData = null,
         _assetsPath = null,
+        _onError = onError,
         _builder = MapJsonViewBuilder(
           map,
+          onError,
           jsonViewTheme: theme,
         ),
         super(key: key);
 
   final Map<String, dynamic>? _mapData;
   final String? _stringData;
   final String? _assetsPath;
+  final Widget _onError;
   final JsonViewBuilder _builder;
   static PrimitiveJsonItemBuilder? primitiveJsonItemBuilder;
 
@@ -82,6 +92,7 @@ class _JsonViewState extends State<JsonView> {
         jsonView = BaseJsonView(
           jsonData: jsonData,
           assetsPath: widget._assetsPath,
+          onError: widget._onError,
           jsonViewTheme: widget._builder.jsonViewTheme,
         );
         break;

lib/src/utils/asset_loader.dart

@@ -6,8 +6,8 @@ abstract class AssetLoader {
     return rootBundle.loadString(path);
   }
 
-  static Future<dynamic> getAssetJson(String filePath) async {
+  static Future<dynamic> getAssetJson(String filePath, onError) async {
     final jsonString = await _loadAssets(filePath);
-    return JsonConverter.jsonStringToObject(jsonString);
+    return JsonConverter.jsonStringToObject(jsonString, onError);
   }
 }

lib/src/utils/converter.dart

@@ -1,9 +1,12 @@
 import 'dart:convert';
 
 abstract class JsonConverter {
-  static dynamic jsonStringToObject(String jsonString) {
-    assert(canConverToObject(jsonString));
-    return json.decode(jsonString);
+  static dynamic jsonStringToObject(String jsonString, dynamic onError) {
+    try {
+      return json.decode(jsonString);
+    } catch (_) {
+      return onError;
+    }
   }
 
   static bool canConverToObject(String jsonString) {

lib/src/widgets/base_json_view.dart

@@ -9,10 +9,12 @@ class BaseJsonView extends StatefulWidget {
     Key? key,
     required this.jsonViewTheme,
     this.jsonData,
+    required this.onError,
     this.assetsPath,
   }) : super(key: key);
 
   final String? jsonData;
+  final Widget onError;
   final JsonViewTheme jsonViewTheme;
   final String? assetsPath;
 
@@ -31,7 +33,8 @@ class _BaseJsonViewState extends State<BaseJsonView> {
 
   Future<void> _loadAssetsJson() async {
     if (widget.assetsPath != null) {
-      final json = await AssetLoader.getAssetJson(widget.assetsPath!);
+      final json =
+          await AssetLoader.getAssetJson(widget.assetsPath!, widget.onError);
       _assetsJsonString = _encoder.convert(json);
       setState(() {});
     }

lib/src/widgets/json_loader_item.dart

@@ -7,10 +7,12 @@ class JsonLoaderItem extends StatefulWidget {
   const JsonLoaderItem({
     Key? key,
     required this.path,
+    required this.onError,
     required this.jsonViewTheme,
   }) : super(key: key);
   final String path;
   final JsonViewTheme jsonViewTheme;
+  final Widget onError;
 
   @override
   State<JsonLoaderItem> createState() => _JsonLoaderItemState();
@@ -31,7 +33,7 @@ class _JsonLoaderItemState extends State<JsonLoaderItem> {
   }
 
   Future<void> _initializeBuilder() async {
-    final json = await AssetLoader.getAssetJson(widget.path);
+    final json = await AssetLoader.getAssetJson(widget.path, widget.onError);
     setState(() {
       _commonBuilder = CommonJsonViewBuilder(
         json,