Optimize mobile - Avoid creating unnecessary widgets (#268)

* Avoid creating unnecessary widgets

* more flexible null handling and runtime errors prevention

mobile/lib/modules/search/providers/search_page_state.provider.dart

@@ -62,11 +62,7 @@ final getCuratedLocationProvider =
   final SearchService searchService = ref.watch(searchServiceProvider);
 
   var curatedLocation = await searchService.getCuratedLocation();
-  if (curatedLocation != null) {
-    return curatedLocation;
-  } else {
-    return [];
-  }
+  return curatedLocation ?? [];
 });
 
 final getCuratedObjectProvider =
@@ -74,9 +70,6 @@ final getCuratedObjectProvider =
   final SearchService searchService = ref.watch(searchServiceProvider);
 
   var curatedObject = await searchService.getCuratedObjects();
-  if (curatedObject != null) {
-    return curatedObject;
-  } else {
-    return [];
-  }
+
+  return curatedObject ?? [];
 });

mobile/lib/modules/search/views/search_page.dart

@@ -176,9 +176,8 @@ class SearchPage extends HookConsumerWidget {
                 _buildThings()
               ],
             ),
-            isSearchEnabled
-                ? SearchSuggestionList(onSubmitted: _onSearchSubmitted)
-                : Container(),
+            if (isSearchEnabled)
+              SearchSuggestionList(onSubmitted: _onSearchSubmitted),
           ],
         ),
       ),

mobile/lib/modules/search/views/search_result_page.dart

@@ -166,7 +166,7 @@ class SearchResultPage extends HookConsumerWidget {
         }
       }
 
-      return Container();
+      return const SizedBox();
     }
 
     return Scaffold(
@@ -198,9 +198,8 @@ class SearchResultPage extends HookConsumerWidget {
         child: Stack(
           children: [
             _buildSearchResult(),
-            isNewSearch.value
-                ? SearchSuggestionList(onSubmitted: _onSearchSubmitted)
-                : Container(),
+            if (isNewSearch.value)
+              SearchSuggestionList(onSubmitted: _onSearchSubmitted),
           ],
         ),
       ),