refactor: Client in ChatPage

lib/pages/chat/chat.dart

@@ -47,7 +47,7 @@ class Chat extends StatefulWidget {
 class ChatController extends State<Chat> {
   Room? room;
 
-  Client? sendingClient;
+  late Client sendingClient;
 
   Timeline? timeline;
 
@@ -250,6 +250,7 @@ class ChatController extends State<Chat> {
     inputFocus.addListener(_inputFocusListener);
     _loadDraft();
     super.initState();
+    sendingClient = Matrix.of(context).client;
   }
 
   void updateView() {
@@ -324,7 +325,7 @@ class ChatController extends State<Chat> {
 
   TextEditingController sendController = TextEditingController();
 
-  void setSendingClient(Client? c) {
+  void setSendingClient(Client c) {
     // first cancle typing with the old sending client
     if (currentlyTyping) {
       // no need to have the setting typing to false be blocking

lib/pages/chat/chat_input_row.dart

@@ -296,7 +296,7 @@ class _ChatAccountPicker extends StatelessWidget {
     return Padding(
       padding: const EdgeInsets.all(8.0),
       child: FutureBuilder<Profile>(
-        future: controller.sendingClient!.fetchOwnProfile(),
+        future: controller.sendingClient.fetchOwnProfile(),
         builder: (context, snapshot) => PopupMenuButton<String>(
           onSelected: (mxid) => _popupMenuButtonSelected(mxid, context),
           itemBuilder: (BuildContext context) => clients

lib/pages/chat/chat_view.dart

@@ -139,9 +139,7 @@ class ChatView extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    final client = Matrix.of(context).client;
-    controller.sendingClient ??= client;
-    controller.room = controller.sendingClient!.getRoomById(controller.roomId!);
+    controller.room = controller.sendingClient.getRoomById(controller.roomId!);
     controller.readMarkerEventId ??= controller.room!.fullyRead;
     if (controller.room == null) {
       return Scaffold(