[LLC] Fix tests

Signed-off-by: Sahil Kumar <[email protected]>

packages/stream_chat/lib/src/api/channel.dart

@@ -301,8 +301,7 @@ class Channel {
       user: _client.state.user,
       quotedMessage: quotedMessage,
       status: MessageSendingStatus.sending,
-      attachments: [
-        ...message.attachments.map(
+      attachments: message.attachments?.map(
         (it) {
           if (it.uploadState.isSuccess) return it;
           return it.copyWith(
@@ -312,8 +311,7 @@ class Channel {
             ),
           );
         },
-        )
-      ],
+      )?.toList(),
     );
 
     if (message.parentId != null && message.id == null) {
@@ -328,6 +326,7 @@ class Channel {
     state?.addMessage(message);
 
     try {
+      if (message.attachments?.isNotEmpty == true) {
         final attachmentsUploadCompleter = Completer<Message>();
         _messageAttachmentsUploadCompleter[message.id] =
             attachmentsUploadCompleter;
@@ -338,6 +337,7 @@ class Channel {
         ));
 
         message = await attachmentsUploadCompleter.future;
+      }
 
       final response = await _client.post(
         '$_channelURL/message',
@@ -374,8 +374,7 @@ class Channel {
     message = message.copyWith(
       status: MessageSendingStatus.updating,
       updatedAt: message.updatedAt ?? DateTime.now(),
-      attachments: [
-        ...message.attachments.map(
+      attachments: message.attachments?.map(
         (it) {
           if (it.uploadState.isSuccess) return it;
           return it.copyWith(
@@ -385,13 +384,13 @@ class Channel {
             ),
           );
         },
-        )
-      ],
+      )?.toList(),
     );
 
     state?.addMessage(message);
 
     try {
+      if (message.attachments?.isNotEmpty == true) {
         final attachmentsUploadCompleter = Completer<Message>();
         _messageAttachmentsUploadCompleter[message.id] =
             attachmentsUploadCompleter;
@@ -402,6 +401,7 @@ class Channel {
         ));
 
         message = await attachmentsUploadCompleter.future;
+      }
 
       final response = await _client.updateMessage(message);
       state?.addMessage(response?.message?.copyWith(