chore: Display normal Slider when no waveform provided in audioplayer

lib/pages/chat/events/audio_player.dart

@@ -179,12 +179,12 @@ class AudioPlayerState extends State<AudioPlayerWidget> {
     return '${duration.inMinutes.toString().padLeft(2, '0')}:${(duration.inSeconds % 60).toString().padLeft(2, '0')}';
   }
 
-  List<int> _getWaveform() {
+  List<int>? _getWaveform() {
     final eventWaveForm = widget.event.content
         .tryGetMap<String, dynamic>('org.matrix.msc1767.audio')
         ?.tryGetList<int>('waveform');
     if (eventWaveForm == null || eventWaveForm.isEmpty) {
-      return List<int>.filled(AudioPlayerWidget.wavesCount, 500);
+      return null;
     }
     while (eventWaveForm.length < AudioPlayerWidget.wavesCount) {
       for (var i = 0; i < eventWaveForm.length; i = i + 2) {
@@ -200,7 +200,7 @@ class AudioPlayerState extends State<AudioPlayerWidget> {
     return eventWaveForm.map((i) => i > 1024 ? 1024 : i).toList();
   }
 
-  late final List<int> waveform;
+  late final List<int>? _waveform;
 
   void _toggleSpeed() async {
     final audioPlayer = this.audioPlayer;
@@ -229,12 +229,13 @@ class AudioPlayerState extends State<AudioPlayerWidget> {
   @override
   void initState() {
     super.initState();
-    waveform = _getWaveform();
+    _waveform = _getWaveform();
   }
 
   @override
   Widget build(BuildContext context) {
     final theme = Theme.of(context);
+    final waveform = _waveform;
 
     final statusText = this.statusText ??= _durationString ?? '00:00';
     final audioPlayer = this.audioPlayer;
@@ -290,34 +291,35 @@ class AudioPlayerState extends State<AudioPlayerWidget> {
                 Expanded(
                   child: Stack(
                     children: [
-                      Padding(
-                        padding: const EdgeInsets.symmetric(horizontal: 16.0),
-                        child: Row(
-                          children: [
-                            for (var i = 0;
-                                i < AudioPlayerWidget.wavesCount;
-                                i++)
-                              Expanded(
-                                child: Container(
-                                  height: 32,
-                                  alignment: Alignment.center,
+                      if (waveform != null)
+                        Padding(
+                          padding: const EdgeInsets.symmetric(horizontal: 16.0),
+                          child: Row(
+                            children: [
+                              for (var i = 0;
+                                  i < AudioPlayerWidget.wavesCount;
+                                  i++)
+                                Expanded(
                                   child: Container(
-                                    margin: const EdgeInsets.symmetric(
-                                      horizontal: 1,
+                                    height: 32,
+                                    alignment: Alignment.center,
+                                    child: Container(
+                                      margin: const EdgeInsets.symmetric(
+                                        horizontal: 1,
+                                      ),
+                                      decoration: BoxDecoration(
+                                        color: i < wavePosition
+                                            ? widget.color
+                                            : widget.color.withAlpha(128),
+                                        borderRadius: BorderRadius.circular(64),
+                                      ),
+                                      height: 32 * (waveform[i] / 1024),
                                     ),
-                                    decoration: BoxDecoration(
-                                      color: i < wavePosition
-                                          ? widget.color
-                                          : widget.color.withAlpha(128),
-                                      borderRadius: BorderRadius.circular(64),
-                                    ),
-                                    height: 32 * (waveform[i] / 1024),
                                   ),
                                 ),
-                              ),
-                          ],
+                            ],
+                          ),
                         ),
-                      ),
                       SizedBox(
                         height: 32,
                         child: Slider(
@@ -325,8 +327,12 @@ class AudioPlayerState extends State<AudioPlayerWidget> {
                                   widget.event.room.client.userID
                               ? theme.colorScheme.onPrimary
                               : theme.colorScheme.primary,
-                          activeColor: Colors.transparent,
-                          inactiveColor: Colors.transparent,
+                          activeColor: waveform == null
+                              ? widget.color
+                              : Colors.transparent,
+                          inactiveColor: waveform == null
+                              ? widget.color.withAlpha(128)
+                              : Colors.transparent,
                           max: maxPosition,
                           value: currentPosition,
                           onChanged: (position) => audioPlayer == null