[UI-KIT] Fix channel_image.dart, remove defaultChannelPreview from theme

Signed-off-by: xsahil03x <[email protected]>

packages/stream_chat_flutter/lib/src/stream_chat_theme.dart

@@ -103,7 +103,6 @@ class StreamChatThemeData {
     required this.otherMessageTheme,
     required this.ownMessageTheme,
     required this.messageInputTheme,
-    required this.defaultChannelImage,
     required this.defaultUserImage,
     required this.primaryIconTheme,
     required this.reactionIcons,
@@ -145,9 +144,6 @@ class StreamChatThemeData {
   /// Theme dedicated to the [MessageInput] widget
   final MessageInputTheme messageInputTheme;
 
-  /// The widget that will be built when the channel image is unavailable
-  final Widget Function(BuildContext, Channel) defaultChannelImage;
-
   /// The widget that will be built when the user image is unavailable
   final Widget Function(BuildContext, User) defaultUserImage;
 
@@ -179,7 +175,6 @@ class StreamChatThemeData {
         textTheme: this.textTheme.merge(textTheme),
         colorTheme: this.colorTheme.merge(colorTheme),
         primaryIconTheme: this.primaryIconTheme.merge(primaryIconTheme),
-        defaultChannelImage: defaultChannelImage ?? this.defaultChannelImage,
         defaultUserImage: defaultUserImage ?? this.defaultUserImage,
         channelPreviewTheme:
             this.channelPreviewTheme.merge(channelPreviewTheme),
@@ -199,7 +194,6 @@ class StreamChatThemeData {
       textTheme: textTheme.merge(other.textTheme),
       colorTheme: colorTheme.merge(other.colorTheme),
       primaryIconTheme: other.primaryIconTheme,
-      defaultChannelImage: other.defaultChannelImage,
       defaultUserImage: other.defaultUserImage,
       channelPreviewTheme: channelPreviewTheme.merge(other.channelPreviewTheme),
       channelTheme: channelTheme.merge(other.channelTheme),
@@ -223,7 +217,6 @@ class StreamChatThemeData {
       textTheme: textTheme,
       colorTheme: colorTheme,
       primaryIconTheme: iconTheme,
-      defaultChannelImage: (context, channel) => const SizedBox(),
       defaultUserImage: (context, user) => Center(
         child: CachedNetworkImage(
           filterQuality: FilterQuality.high,