null safety

lib/pages/widgets/title_with_add_button.dart

@@ -6,11 +6,11 @@ import 'package:flutter/material.dart';
 import 'callbacks.dart';
 
 class TitleWithAddButton extends StatelessWidget {
-  final IconData iconData;
-  final String titleKey;
-  final OnTap onTap;
+  final IconData? iconData;
+  final String? titleKey;
+  final OnTap? onTap;
 
-  const TitleWithAddButton({Key key, this.iconData, this.titleKey, this.onTap})
+  const TitleWithAddButton({Key? key, this.iconData, this.titleKey, this.onTap})
       : super(key: key);
 
   @override
@@ -28,7 +28,7 @@ class TitleWithAddButton extends StatelessWidget {
             ),
             LocalText(
               context,
-              titleKey,
+              titleKey!,
               color: Colors.black54,
               fontSize: 20,
             )
@@ -40,7 +40,7 @@ class TitleWithAddButton extends StatelessWidget {
             : Padding(
                 padding: const EdgeInsets.only(right: 0),
                 child: IconButton(
-                    onPressed: () => onTap(),
+                    onPressed: () => onTap!(),
                     icon: Icon(
                       Icons.add_circle,
                       color: primaryColor,