Updated example and readme

example/lib/main.dart

@@ -2,9 +2,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:rive/rive.dart';
 
-void main() {
-  runApp(MyApp());
-}
+void main() => runApp(MyApp());
 
 class MyApp extends StatefulWidget {
   @override
@@ -32,8 +30,7 @@ class _MyHomePageState extends State<MyHomePage> {
     setState(() => _controller.isActive = !_controller.isActive);
   }
 
-  /// We track if the animation is playing by whether or not the controller is
-  /// running.
+  /// Tracks if the animation is playing by whether controller is running.
   bool get isPlaying => _controller?.isActive ?? false;
 
   Artboard _riveArtboard;
@@ -46,19 +43,16 @@ class _MyHomePageState extends State<MyHomePage> {
     // download this. The RiveFile just expects a list of bytes.
     rootBundle.load('assets/off_road_car.riv').then(
       (data) async {
-        var file = RiveFile();
+        final file = RiveFile();
 
         // Load the RiveFile from the binary data.
-        var success = file.import(data);
-        if (success) {
-          // The artboard is the root of the animation and is what gets drawn
-          // into the Rive widget.
-          var artboard = file.mainArtboard;
+        if (file.import(data)) {
+          // The artboard is the root of the animation and gets drawn in the
+          // Rive widget.
+          final artboard = file.mainArtboard;
           // Add a controller to play back a known animation on the main/default
           // artboard.We store a reference to it so we can toggle playback.
-          artboard.addController(
-            _controller = SimpleAnimation('idle'),
-          );
+          artboard.addController(_controller = SimpleAnimation('idle'));
           setState(() => _riveArtboard = artboard);
         }
       },

example/pubspec.lock

@@ -7,49 +7,49 @@ packages:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.5.0-nullsafety.1"
+    version: "2.5.0-nullsafety.2"
   boolean_selector:
     dependency: transitive
     description:
       name: boolean_selector
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.0-nullsafety.1"
+    version: "2.1.0-nullsafety.2"
   characters:
     dependency: transitive
     description:
       name: characters
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0-nullsafety.3"
+    version: "1.1.0-nullsafety.4"
   charcode:
     dependency: transitive
     description:
       name: charcode
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0-nullsafety.1"
+    version: "1.2.0-nullsafety.2"
   clock:
     dependency: transitive
     description:
       name: clock
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0-nullsafety.1"
+    version: "1.1.0-nullsafety.2"
   collection:
     dependency: transitive
     description:
       name: collection
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.15.0-nullsafety.3"
+    version: "1.15.0-nullsafety.4"
   fake_async:
     dependency: transitive
     description:
       name: fake_async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0-nullsafety.1"
+    version: "1.2.0-nullsafety.2"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -73,21 +73,21 @@ packages:
       name: matcher
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.12.10-nullsafety.1"
+    version: "0.12.10-nullsafety.2"
   meta:
     dependency: transitive
     description:
       name: meta
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.3.0-nullsafety.3"
+    version: "1.3.0-nullsafety.5"
   path:
     dependency: transitive
     description:
       name: path
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.8.0-nullsafety.1"
+    version: "1.8.0-nullsafety.2"
   rive:
     dependency: "direct main"
     description:
@@ -106,55 +106,55 @@ packages:
       name: source_span
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.8.0-nullsafety.2"
+    version: "1.8.0-nullsafety.3"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.10.0-nullsafety.1"
+    version: "1.10.0-nullsafety.5"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.0-nullsafety.1"
+    version: "2.1.0-nullsafety.2"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0-nullsafety.1"
+    version: "1.1.0-nullsafety.2"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0-nullsafety.1"
+    version: "1.2.0-nullsafety.2"
   test_api:
     dependency: transitive
     description:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.19-nullsafety.2"
+    version: "0.2.19-nullsafety.4"
   typed_data:
     dependency: transitive
     description:
       name: typed_data
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.3.0-nullsafety.3"
+    version: "1.3.0-nullsafety.4"
   vector_math:
     dependency: transitive
     description:
       name: vector_math
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.0-nullsafety.3"
+    version: "2.1.0-nullsafety.4"
 sdks:
-  dart: ">=2.10.0-110 <2.11.0"
+  dart: ">=2.11.0-0.0 <2.12.0"