clear data before tree query

src/views/questioncenter/components/generate-tabs/paper-by-hand.vue

@@ -295,6 +295,7 @@ export default {
       await this._renderQuestions(res)
     },
     async queryQuestions() {
+      if (!this.currentNode) return
       const commit = {
         pageNum: this.pageNum,
         pageSize: this.pageSize,