fix: 可选字段处理

- 为搜索条目中的可选字段进行判断并处理

server/utils/search-converters.ts

@@ -8,16 +8,16 @@ export const converters: {
     id: item.id,
     type: 'product',
     title: item.name,
-    summary: item.summary,
-    thumbnail: `/api/assets/${item.cover}`,
+    summary: item?.summary ?? '',
+    thumbnail: item?.cover ? `/api/assets/${item.cover}` : undefined,
   }),
 
   solutions: (item: MeiliIndexMap['solutions']): SearchItemView => ({
     id: item.id,
     type: 'solution',
     title: item.title,
-    summary: item.summary,
-    thumbnail: `/api/assets/${item.cover}`,
+    summary: item?.summary ?? '',
+    thumbnail: item?.cover ? `/api/assets/${item.cover}` : undefined,
   }),
 
   questions: (item: MeiliIndexMap['questions']): SearchItemView => ({