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;
@@ -290,6 +291,7 @@ class AudioPlayerState extends State<AudioPlayerWidget> {
                 Expanded(
                   child: Stack(
                     children: [
+                      if (waveform != null)
                         Padding(
                           padding: const EdgeInsets.symmetric(horizontal: 16.0),
                           child: Row(
@@ -325,8 +327,12 @@ class AudioPlayerState extends State<AudioPlayerWidget> {
                                   widget.event.room.client.userID
                               ? theme.colorScheme.onPrimary
                               : theme.colorScheme.primary,
-                          activeColor: Colors.transparent,
+                          activeColor: waveform == null
-                          inactiveColor: Colors.transparent,
+                              ? widget.color
+                              : Colors.transparent,
+                          inactiveColor: waveform == null
+                              ? widget.color.withAlpha(128)
+                              : Colors.transparent,
                           max: maxPosition,
                           value: currentPosition,
                           onChanged: (position) => audioPlayer == null