fix简答题重置

src/features/OnlineExam/Examing/TextQuestionView.vue

@@ -39,7 +39,7 @@ export default {
     },
     studentAnswer() {
       let realAnswer = null;
-      if (this.studentAnswer || this.studentAnswer.trim()) {
+      if (this.studentAnswer) {
         // 如果有实际内容
         realAnswer = this.studentAnswer;
       }