Fix CastButton and CastIcon

- CastButton padding
- CastIcon `setState() after dispose()`

lib/src/cast/widgets/CastButton.dart

@@ -5,16 +5,21 @@ import 'CastIcon.dart';
 
 class CastButton extends StatelessWidget {
   final Color color;
+  final EdgeInsets padding;
 
   CastButton({
-    required this.color,
+    this.color = const Color(0xFFFFFFFF), // white
+    this.padding = const EdgeInsets.all(8.0),
   });
 
   @override
   Widget build(BuildContext context) {
     return GestureDetector(
-        child: CastIcon(
-          color: color,
+        child: Padding(
+          padding: padding,
+          child:  CastIcon(
+            color: color,
+          ),
         ),
         onTap: () => FlutterCastFramework.castContext.showCastChooserDialog());
   }

lib/src/cast/widgets/CastIcon.dart

@@ -39,7 +39,10 @@ class _CastIconState extends State<CastIcon> with TickerProviderStateMixin {
   }
 
   void _onCastStateChanged() {
+    if (!mounted) return;
+
     setState(() {
+      if (!mounted) return;
       _castState = FlutterCastFramework.castContext.state.value;
     });
   }
@@ -101,6 +104,7 @@ class _ConnectingIconState extends State<_ConnectingIcon> {
     if (!this.mounted) return;
 
     setState(() {
+      if (!mounted) return;
       _frameIndex = 0;
       isAnimating = true;
     });
@@ -111,9 +115,12 @@ class _ConnectingIconState extends State<_ConnectingIcon> {
 
     if (_frameIndex < _connectingAnimationFrames.length - 1) {
       await Future.delayed(const Duration(milliseconds: 300));
-      setState(() {
-        _frameIndex += 1;
-      });
+      if (mounted) {
+        setState(() {
+          if (!mounted) return;
+          _frameIndex += 1;
+        });
+      }
     } else {
       // When I reach the end, I re-start from the beginning
       await Future.delayed(const Duration(seconds: 1));