fix(功能用例): 没有选择文件直接点击上传会报错

--bug=1009959 --user=李敏 【没有选择文件直接点击上传会报错】https://www.tapd.cn/55049933/bugtrace/bugs/view?bug_id=1155049933001009959

frontend/src/business/components/track/case/components/import/TestCaseCommonImport.vue

@@ -71,9 +71,9 @@
     </el-row>
 
     <el-row style="text-align: right" >
-      <div v-if="showContinueBtn" style="margin-right: 20px;margin-bottom: 10px;">
-        <el-checkbox :value="true" :disabled="true">{{ $t('test_track.case.import.ignore_error') }}</el-checkbox>
-      </div>
+<!--      <div v-if="showContinueBtn" style="margin-right: 20px;margin-bottom: 10px;">-->
+<!--        <el-checkbox :value="true" :disabled="true">{{ $t('test_track.case.import.ignore_error') }}</el-checkbox>-->
+<!--      </div>-->
       <el-button v-if="showContinueBtn" type="primary" @click="upload(true)">
         {{ $t('test_track.case.import.continue_upload') }}
       </el-button>
@@ -170,6 +170,7 @@ export default {
     },
     handleRemove(file, fileList) {
       this.lastFile = null;
+      this.showContinueBtn = false;
     },
     upload(isIgnore) {
       this.isLoading = false;
@@ -180,6 +181,10 @@ export default {
         versionId: this.versionId,
         ignore: isIgnore
       };
+      if (this.lastFile == null || this.lastFile == undefined) {
+        this.$warning(this.$t('test_track.case.import.import_file_tips'));
+        return;
+      }
       this.result = this.$fileUpload('/test/case/import',
         this.lastFile, null, param, response => {
         let res = response.data;

frontend/src/i18n/en-US.js

@@ -2038,6 +2038,7 @@ export default {
         import_update: "Import Update",
         import_tip1: "The ID is required when the \"Test Case Custom ID\" switch is turned on in the project settings",
         import_tip2: "ID is required when importing and updating",
+        import_file_tips: "Please upload the file first!",
       },
       export: {
         export: "Export cases",

frontend/src/i18n/zh-CN.js

@@ -2036,6 +2036,7 @@ export default {
         import_update: "导入更新",
         import_tip1: "项目设置中“测试用例自定义ID” 开关开启时ID为必填项",
         import_tip2: "导入更新时ID为必填项",
+        import_file_tips: "请先上传文件！",
       },
       export: {
         export: "导出用例",

frontend/src/i18n/zh-TW.js

@@ -2036,6 +2036,7 @@ export default {
         import_update: "導入更新",
         import_tip1: "項目設置中「測試用例自定義ID」 開關開啟時ID為必填項",
         import_tip2: "導入更新時ID為必填項",
+        import_file_tips: "請先上傳文件！",
       },
       export: {
         export: "導出用例",