bug fixes

src/modules/student/lab/views/Report.vue

@@ -127,7 +127,7 @@ watchEffect(() => {
       url,
       name: file.name,
       type: '1',
-      file_type: file.type,
+      file_type: file.type || 'png',
       updated_time: formatted.value,
       upload_time: formatted.value
     })