refactor(details): remove country chip from details

- Removed headquarters chip
- Fixed non-null assertion operator usage

Author: fulleni

lib/headline-details/view/headline_details_page.dart

@@ -400,11 +400,10 @@ class _HeadlineDetailsPageState extends State<HeadlineDetailsPage> {
     if (headline.source != null) {
       chips.add(
         GestureDetector(
-          // Added GestureDetector
           onTap: () {
             context.push(
               Routes.sourceDetails,
-              extra: EntityDetailsPageArguments(entity: headline.source),
+              extra: EntityDetailsPageArguments(entity: headline.source!),
             );
           },
           child: Chip(
@@ -445,35 +444,15 @@ class _HeadlineDetailsPageState extends State<HeadlineDetailsPage> {
       );
     }
 
-    if (headline.source?.headquarters != null) {
-      final country = headline.source!.headquarters!;
-      chips.add(
-        Chip(
-          // Country chip is usually not tappable to a details page in this context
-          avatar: CircleAvatar(
-            radius: chipAvatarSize / 2,
-            backgroundColor: Colors.transparent,
-            backgroundImage: NetworkImage(country.flagUrl),
-            onBackgroundImageError: (exception, stackTrace) {},
-          ),
-          label: Text(country.name),
-          labelStyle: chipLabelStyle,
-          backgroundColor: chipBackgroundColor,
-          padding: chipPadding,
-          visualDensity: chipVisualDensity,
-          materialTapTargetSize: chipMaterialTapTargetSize,
-        ),
-      );
-    }
+    // Country chip for headline.source.headquarters removed.
 
     if (headline.category != null) {
       chips.add(
         GestureDetector(
-          // Added GestureDetector
           onTap: () {
             context.push(
               Routes.categoryDetails,
-              extra: EntityDetailsPageArguments(entity: headline.category),
+              extra: EntityDetailsPageArguments(entity: headline.category!),
             );
           },
           child: Chip(
@@ -551,6 +530,7 @@ class _HeadlineDetailsPageState extends State<HeadlineDetailsPage> {
                                 extra: similarHeadline,
                               ),
                         );
+                        break;
                       case HeadlineImageStyle.smallThumbnail:
                         tile = HeadlineTileImageStart(
                           headline: similarHeadline,
@@ -561,6 +541,7 @@ class _HeadlineDetailsPageState extends State<HeadlineDetailsPage> {
                                 extra: similarHeadline,
                               ),
                         );
+                        break;
                       case HeadlineImageStyle.largeThumbnail:
                         tile = HeadlineTileImageTop(
                           headline: similarHeadline,
@@ -571,12 +552,13 @@ class _HeadlineDetailsPageState extends State<HeadlineDetailsPage> {
                                 extra: similarHeadline,
                               ),
                         );
+                        break;
                     }
                     return tile;
                   },
                 ),
               );
-            }, childCount: loadedState.similarHeadlines.length,),
+            }, childCount: loadedState.similarHeadlines.length),
           ),
           _ => const SliverToBoxAdapter(child: SizedBox.shrink()),
         };