fix: 修复创建题目时无法切换题型的bug

src/views/quiz/components/QuestionEditorFactory.vue

@@ -10,10 +10,12 @@
         placeholder="选择相关知识点"
       />
       推荐知识点：
-      <c-button :right="6" :key="item" :theme="selectedKnowledgeIdList.indexOf(item) !== -1 ? 'green' : ''"
-                v-for="item of recommended" @click="pushToSelectedKnowledgeIdList(item)">
-        {{knowledgeTreeNaming[item]}}
-      </c-button>
+      <span v-if="selectedKnowledgeIdList&&JSON.stringify(selectedKnowledgeIdList)!=='{}'">
+        <c-button :right="6" :key="item" :theme="selectedKnowledgeIdList.indexOf(item) !== -1 ? 'green' : ''"
+                  v-for="item of recommended" @click="pushToSelectedKnowledgeIdList(item)">
+          {{knowledgeTreeNaming[item]}}
+        </c-button>
+      </span>
     </template>
 
     <div v-else class="mt-24">知识点加载中...</div>