执行 android，报错了，获取不到页面元素

2018-09-15 14:11:32 WARN [AppiumClient.$anonfun$getPageSource$1.340] get page source error
2018-09-15 14:11:32 WARN [Crawler.refreshPage.562] page source get fail, go back
2018-09-15 14:11:32 INFO [Crawler.setElementAction.660] set action to back
2018-09-15 14:11:32 INFO [Crawler.runStartupScript.236] first refresh
2018-09-15 14:11:32 INFO [Crawler.doElementAction.976] current element = _startupActions-Start-0
2018-09-15 14:11:32 INFO [Crawler.doElementAction.977] current index = 0
2018-09-15 14:11:32 INFO [Crawler.doElementAction.978] current action =
2018-09-15 14:11:32 INFO [Crawler.doElementAction.979] current url =
2018-09-15 14:11:32 INFO [Crawler.doElementAction.980] current xpath = startupActions-Start-0
2018-09-15 14:11:32 INFO [Crawler.doElementAction.981] current tag path = _startupActions-Start-0
2018-09-15 14:11:32 INFO [Crawler.doElementAction.982] current file name = _
2018-09-15 14:11:32 INFO [Crawler.doElementAction.983] current uri = startupActions-Start-0 startupActions
Exception in thread "main" java.util.NoSuchElementException: last of empty ListBuffer
at scala.collection.mutable.ListBuffer.last(ListBuffer.scala:401)
at com.testerhome.appcrawler.DataRecord.last(DataRecord.scala:40)
at com.testerhome.appcrawler.Crawler.doElementAction(Crawler.scala:985)
at com.testerhome.appcrawler.Crawler.runStartupScript(Crawler.scala:238)
at com.testerhome.appcrawler.Crawler.start(Crawler.scala:152)
at com.testerhome.appcrawler.AppCrawler$.startCrawl(AppCrawler.scala:344)
at com.testerhome.appcrawler.AppCrawler$.parseParams(AppCrawler.scala:312)
at com.testerhome.appcrawler.AppCrawler$.main(AppCrawler.scala:92)
at com.testerhome.appcrawler.AppCrawler.main(AppCrawler.scala)

[HTTP] <-- POST /wd/hub/session/74fdb256-4956-44db-a632-e8e85437d963/execute/sync 405 10 ms - 3527
[HTTP]
[debug] [AndroidBootstrap] Emitting alert message...
[debug] [AndroidBootstrap] [BOOTSTRAP LOG] [debug] Emitting system alert message

Publish JUnit test result report 检测不到 Xml 文件，一般是什么情况