more practice tweaks

lib/pangea/analytics_misc/put_analytics_controller.dart

@@ -111,7 +111,7 @@ class PutAnalyticsController {
     String? targetId,
   }) {
     final level = _pangeaController.getAnalytics.constructListModel.level;
-    _addLocalMessage(eventId, constructs).then(
+    _addLocalMessage(eventId, List.from(constructs)).then(
       (_) => _sendAnalytics(level, targetId, constructs),
     );
   }

lib/pangea/toolbar/message_practice/reading_assistance_input_bar.dart

@@ -176,11 +176,10 @@ class _ReadingAssistanceBarContent extends StatelessWidget {
         }
 
         if (target == null) {
-          return Center(
-            child: Text(
-              L10n.of(context).selectForGrammar,
-              style: Theme.of(context).textTheme.bodyLarge,
-              textAlign: TextAlign.center,
+          return const Center(
+            child: Icon(
+              Symbols.fitness_center,
+              size: 60.0,
             ),
           );
         }

lib/pangea/toolbar/message_practice/token_practice_button.dart

@@ -98,6 +98,7 @@ class TokenPracticeButton extends StatelessWidget {
           child = _MorphMatchButton(
             active: _isSelected,
             textColor: textColor,
+            width: tokenButtonHeight,
             onTap: () => controller.onSelectMorph(
               MorphSelection(
                 token,
@@ -198,10 +199,12 @@ class _MorphMatchButton extends StatelessWidget {
   final bool active;
   final Color textColor;
   final bool shimmer;
+  final double width;
 
   const _MorphMatchButton({
     required this.active,
     required this.textColor,
+    required this.width,
     this.shimmer = false,
     this.onTap,
   });
@@ -218,7 +221,7 @@ class _MorphMatchButton extends StatelessWidget {
             child: ShimmerBackground(
               enabled: shimmer,
               child: SizedBox(
-                width: 24.0,
+                width: width,
                 child: Center(
                   child: Opacity(
                     opacity: active ? 1.0 : 0.6,
@@ -282,7 +285,6 @@ class _NoActivityContentButton extends StatelessWidget {
             context: context,
           ),
           child: SizedBox(
-            width: 24.0,
             child: Center(
               child: MorphIcon(
                 morphFeature: morphFeature,