fix linter

lib/src/message_input.dart

@@ -324,6 +324,8 @@ class _MessageInputState extends State<MessageInput> {
       ),
     );
 
+    attachment.url = res.file;
+
     setState(() {
       attachment.uploaded = true;
     });
@@ -404,9 +406,9 @@ class _MessageInputState extends State<MessageInput> {
 }
 
 class _SendingAttachment {
-  final String url;
   final File file;
   final FileType type;
+  String url;
   bool uploaded = false;
 
   _SendingAttachment({

lib/src/message_widget.dart

@@ -505,19 +505,21 @@ class _MessageWidgetState extends State<MessageWidget>
                   mainAxisAlignment: MainAxisAlignment.start,
                   children:
                       widget.message.reactionCounts.keys.map((reactionType) {
-                    return Text(
-                      reactionToEmoji[reactionType] ?? '?',
-                    ) as Widget; //TODO refactor
-                  }).toList()
-                        ..add(Padding(
-                          padding: const EdgeInsets.only(left: 4.0),
-                          child: Text(
-                            widget.message.reactionCounts.values
-                                .fold(0, (t, v) => v + t)
-                                .toString(),
-                            style: TextStyle(color: Colors.white),
-                          ),
-                        )))
+                            return Text(
+                              reactionToEmoji[reactionType] ?? '?',
+                            ) as Widget; //TODO refactor
+                          }).toList() +
+                          [
+                            Padding(
+                              padding: const EdgeInsets.only(left: 4.0),
+                              child: Text(
+                                widget.message.reactionCounts.values
+                                    .fold(0, (t, v) => v + t)
+                                    .toString(),
+                                style: TextStyle(color: Colors.white),
+                              ),
+                            )
+                          ])
               : SizedBox(),
         ),
       ),

lib/src/thread_header.dart

@@ -2,8 +2,6 @@ import 'package:flutter/material.dart';
 import 'package:stream_chat/stream_chat.dart';
 import 'package:stream_chat_flutter/src/stream_chat_theme.dart';
 
-import 'stream_channel.dart';
-
 class ThreadHeader extends StatelessWidget implements PreferredSizeWidget {
   final bool showBackButton;
   final VoidCallback onBackPressed;
@@ -19,7 +17,6 @@ class ThreadHeader extends StatelessWidget implements PreferredSizeWidget {
 
   @override
   Widget build(BuildContext context) {
-    final channel = StreamChannel.of(context).channel;
     return AppBar(
       automaticallyImplyLeading: false,
       elevation: 1,