Remove child from AppPage (use builder instead).

lib/app/views/app_page.dart

@@ -33,8 +33,7 @@ final _navExpandedKey = GlobalKey();
 
 class AppPage extends StatelessWidget {
   final Widget? title;
-  final Widget? child;
-  final Widget Function(BuildContext context, bool expanded)? builder;
+  final Widget Function(BuildContext context, bool expanded) builder;
   final Widget Function(BuildContext context)? detailViewBuilder;
   final List<Widget> actions;
   final Widget Function(BuildContext context)? keyActionsBuilder;
@@ -47,8 +46,7 @@ class AppPage extends StatelessWidget {
   const AppPage({
     super.key,
     this.title,
-    this.child,
-    this.builder,
+    required this.builder,
     this.actions = const [],
     this.centered = false,
     this.keyActionsBuilder,
@@ -58,12 +56,8 @@ class AppPage extends StatelessWidget {
     this.onFileDropped,
     this.delayedContent = false,
     this.keyActionsBadge = false,
-  })  : assert(!(onFileDropped != null && fileDropOverlay == null),
-            'Declaring onFileDropped requires declaring a fileDropOverlay'),
-        assert(
-            ((child == null && builder != null) ||
-                (child != null && builder == null)),
-            'Exactly one of child and builder must be declared');
+  }) : assert(!(onFileDropped != null && fileDropOverlay == null),
+            'Declaring onFileDropped requires declaring a fileDropOverlay');
 
   @override
   Widget build(BuildContext context) => LayoutBuilder(
@@ -159,7 +153,7 @@ class AppPage extends StatelessWidget {
   Widget _buildMainContent(BuildContext context, bool expanded) {
     final content = Column(
       children: [
-        child ?? builder!(context, expanded),
+        builder(context, expanded),
         if (actions.isNotEmpty)
           Align(
             alignment: centered ? Alignment.center : Alignment.centerLeft,

lib/app/views/message_page.dart

@@ -59,7 +59,7 @@ class MessagePage extends StatelessWidget {
         onFileDropped: onFileDropped,
         actionButtonBuilder: actionButtonBuilder,
         delayedContent: delayedContent,
-        child: Padding(
+        builder: (context, _) => Padding(
           padding: const EdgeInsets.only(
               left: 8.0, top: 0.0, right: 8.0, bottom: 96.0),
           child: Column(

lib/fido/views/fido_screen.dart

@@ -39,7 +39,7 @@ class FidoScreen extends ConsumerWidget {
               title: Text(l10n.s_webauthn),
               centered: true,
               delayedContent: true,
-              child: const CircularProgressIndicator(),
+              builder: (context, _) => const CircularProgressIndicator(),
             ),
         error: (error, _) {
           final supported = deviceData

lib/fido/views/locked_page.dart

@@ -92,7 +92,7 @@ class FidoLockedPage extends ConsumerWidget {
     return AppPage(
       title: Text(l10n.s_webauthn),
       keyActionsBuilder: hasActions ? _buildActions : null,
-      child: Column(
+      builder: (context, _) => Column(
         children: [
           _PinEntryForm(state, node),
         ],

lib/fido/views/unlocked_page.dart

@@ -365,7 +365,7 @@ class _FidoUnlockedPageState extends ConsumerState<FidoUnlockedPage> {
         title: Text(AppLocalizations.of(context)!.s_webauthn),
         centered: true,
         delayedContent: true,
-        child: const CircularProgressIndicator(),
+        builder: (context, _) => const CircularProgressIndicator(),
       );
 }
 

lib/oath/views/oath_screen.dart

@@ -81,7 +81,7 @@ class _LockedView extends ConsumerWidget {
       keyActionsBuilder: hasActions
           ? (context) => oathBuildActions(context, devicePath, oathState, ref)
           : null,
-      child: Padding(
+      builder: (context, _) => Padding(
         padding: const EdgeInsets.symmetric(vertical: 18),
         child: UnlockForm(
           devicePath,
@@ -259,7 +259,7 @@ class _UnlockedViewState extends ConsumerState<_UnlockedView> {
         ),
         centered: numCreds == null,
         delayedContent: numCreds == null,
-        child: numCreds != null
+        builder: (context, expanded) => numCreds != null
             ? Consumer(
                 builder: (context, ref, _) {
                   return AccountList(