修复表格不显示查看按钮

@@ -297,7 +297,7 @@ onMounted(() => {
             <el-tag :type="tagType(scope.row, item.field)">{{
             tagMethod(scope.row, item.field)
             }}</el-tag>
-             <span v-if="item.btn?.visible?.(scope) !== false && item.btn.visible !== false" class="text_btn" style="position: absolute;right: 0;"
+             <span v-if="item.btn && item.btn?.visible?.(scope) !== false && item.btn?.visible !== false" class="text_btn" style="position: absolute;right: 0;"
               @click="(item.btn.click && !item.btn.disabled && !scope.row.disabled) ? item.btn.click(scope, item.btn) : handleClick(scope, item.btn)"
               v-preReClick>{{ item.btn.label }}</span>
           </div>