bug fix

src/modules/base/components/RuleExam.vue

@@ -133,7 +133,7 @@ export default {
       const examRule = await examRuleDetail();
       this.modalForm = Object.assign({}, initModalForm, examRule || {});
       this.modalForm.examNumberDigit =
-        examRule.examNumberDigit || initModalForm.examNumberDigit;
+        this.modalForm.examNumberDigit || initModalForm.examNumberDigit;
 
       this.modalForm.requiredFields = requiredFields.map(item => {
         return {