Start to fix null safety migration errors

lib/ui/widgets/tablet_mode/conversations/conversation_window.dart

@@ -24,9 +24,9 @@ class ConversationWindow extends StatefulWidget {
   final Function() onClose;
 
   const ConversationWindow({
-    Key key,
-    @required this.convID,
-    @required this.onClose,
+    Key? key,
+    required this.convID,
+    required this.onClose,
   })  : assert(convID != null),
         assert(onClose != null),
         super(key: key);
@@ -36,8 +36,8 @@ class ConversationWindow extends StatefulWidget {
 }
 
 class _ConversationWindowState extends SafeState<ConversationWindow> {
-  Conversation _conversation;
-  String _convTitle;
+  Conversation? _conversation;
+  late String _convTitle;
   bool _error = false;
   bool _collapsed = false;
   bool _hasNewMessages = false;
@@ -71,7 +71,7 @@ class _ConversationWindowState extends SafeState<ConversationWindow> {
     } catch (e, s) {
       _setError(true);
       print("Could not refresh the list of conversations! $e\n$s");
-      showSimpleSnack(context, tr("Could not load conversation information!"));
+      showSimpleSnack(context, tr("Could not load conversation information!")!);
     }
   }
 
@@ -92,7 +92,7 @@ class _ConversationWindowState extends SafeState<ConversationWindow> {
     if (_error)
       return ConversationWindowContainer(
         icon: Icon(Icons.error),
-        title: Text(tr("Error")),
+        title: Text(tr("Error")!),
         onClose: widget.onClose,
         onToggleCollapse: _toggleVisibility,
         isCollapsed: _collapsed,
@@ -100,7 +100,7 @@ class _ConversationWindowState extends SafeState<ConversationWindow> {
             actions: [
               ElevatedButton(
                 onPressed: _refresh,
-                child: Text(tr("Try again").toUpperCase()),
+                child: Text(tr("Try again")!.toUpperCase()),
               )
             ]),
       );
@@ -109,7 +109,7 @@ class _ConversationWindowState extends SafeState<ConversationWindow> {
     if (_conversation == null)
       return ConversationWindowContainer(
         icon: Icon(Icons.message),
-        title: Text(tr("Loading...")),
+        title: Text(tr("Loading...")!),
         onClose: widget.onClose,
         onToggleCollapse: _toggleVisibility,
         isCollapsed: _collapsed,
@@ -123,7 +123,7 @@ class _ConversationWindowState extends SafeState<ConversationWindow> {
       onClose: widget.onClose,
       onToggleCollapse: _toggleVisibility,
       isCollapsed: _collapsed,
-      action: (_conversation.callCapabilities != CallCapabilities.NONE
+      action: (_conversation!.callCapabilities != CallCapabilities.NONE
           ? [IconButton(icon: Icon(Icons.call), onPressed: _startCall)]
           : [])
         ..addAll(<Widget>[
@@ -131,19 +131,19 @@ class _ConversationWindowState extends SafeState<ConversationWindow> {
             itemBuilder: (c) => [
               // Show in full screen
               PopupMenuItem(
-                child: Text(tr("Open in full screen")),
+                child: Text(tr("Open in full screen")!),
                 value: _Actions.OPEN_FULL_SCREEN,
               ),
 
               // Show the list of members
               PopupMenuItem(
-                child: Text(tr("Members")),
+                child: Text(tr("Members")!),
                 value: _Actions.OPEN_MEMBERS,
               ),
 
               // Show conversation settings
               PopupMenuItem(
-                child: Text(tr("Settings")),
+                child: Text(tr("Settings")!),
                 value: _Actions.OPEN_SETTINGS,
               )
             ],
@@ -174,8 +174,8 @@ class _ConversationWindowState extends SafeState<ConversationWindow> {
   }
 
   void _openFullScreen() {
-    MainController.of(context)
-        .openConversation(_conversation, fullScreen: true);
+    MainController.of(context)!
+        .openConversation(_conversation!, fullScreen: true);
     widget.onClose();
   }
 
@@ -189,5 +189,5 @@ class _ConversationWindowState extends SafeState<ConversationWindow> {
     _refresh();
   }
 
-  void _startCall() => MainController.of(context).startCall(_convID);
+  void _startCall() => MainController.of(context)!.startCall(_convID);
 }

lib/ui/widgets/tablet_mode/conversations/conversation_window_container.dart

@@ -8,24 +8,24 @@ import 'package:flutter/material.dart';
 /// @author Pierre Hubert
 
 class ConversationWindowContainer extends StatelessWidget {
-  final Color appBarBgColor;
-  final Widget icon;
+  final Color? appBarBgColor;
+  final Widget? icon;
   final Widget title;
   final void Function() onClose;
   final void Function() onToggleCollapse;
   final bool isCollapsed;
   final Widget body;
-  final List<Widget> action;
+  final List<Widget>? action;
 
   const ConversationWindowContainer({
-    Key key,
+    Key? key,
     this.appBarBgColor,
     this.icon,
-    @required this.title,
-    @required this.onClose,
-    @required this.body,
-    @required this.onToggleCollapse,
-    @required this.isCollapsed,
+    required this.title,
+    required this.onClose,
+    required this.body,
+    required this.onToggleCollapse,
+    required this.isCollapsed,
     this.action,
   })  : assert(title != null),
         assert(onClose != null),
@@ -47,7 +47,7 @@ class ConversationWindowContainer extends StatelessWidget {
                 backgroundColor: appBarBgColor,
                 leading: icon,
                 title: GestureDetector(child: title, onTap: onToggleCollapse),
-                actions: (action == null ? [] : action)
+                actions: action ?? []
                   ..add(
                     IconButton(icon: Icon(Icons.close), onPressed: onClose),
                   ),

lib/ui/widgets/tablet_mode/conversations/conversations_area_widget.dart

@@ -9,14 +9,14 @@ import 'package:flutter/material.dart';
 /// @author Pierre
 
 class ConversationsAreaWidget extends StatefulWidget {
-  const ConversationsAreaWidget({Key key}) : super(key: key);
+  const ConversationsAreaWidget({Key? key}) : super(key: key);
 
   @override
   ConversationsAreaWidgetState createState() => ConversationsAreaWidgetState();
 }
 
 class ConversationsAreaWidgetState extends State<ConversationsAreaWidget> {
-  final _openConversations = Map<int, UniqueKey>();
+  final _openConversations = Map<int?, UniqueKey>();
 
   @override
   Widget build(BuildContext context) {
@@ -31,17 +31,17 @@ class ConversationsAreaWidgetState extends State<ConversationsAreaWidget> {
   Widget _buildOpenButton() => OpenConversationButton();
 
   /// Open a new conversation
-  void openConversations(int convID) {
+  void openConversations(int? convID) {
     if (!_openConversations.containsKey(convID))
       setState(() => _openConversations[convID] = UniqueKey());
   }
 
-  MapEntry<int, Widget> _conversationWindow(int convID, UniqueKey key) =>
+  MapEntry<int?, Widget> _conversationWindow(int? convID, UniqueKey key) =>
       MapEntry(
         convID,
         ConversationWindow(
           key: key,
-          convID: convID,
+          convID: convID!,
           onClose: () => setState(() => _openConversations.remove(convID)),
         ),
       );