环境：电脑--mac npm 下载 appium1.6.3 手机--iphone6s ios9.3.5
命令行打开 appium 运行脚本总是报这个错 请问有谁遇到过吗
报错附近 log

[XCUITest] Launching WebDriverAgent on the device
[debug] [XCUITest] Carthage found: /usr/local/bin/carthage
[debug] [XCUITest] Killing hanging processes
[debug] [XCUITest] Using real device logger 'idevicesyslog'
[debug] [XCUITest] Beginning test with command 'xcodebuild build test -project /usr/local/lib/node_modules/appium/node_modules/appium-xcuitest-driver/WebDriverAgent/WebDriverAgent.xcodeproj -scheme WebDriverAgentRunner -destination id=842c6615c76e1d00caf8a010e70feb40ce1c95ba -configuration Debug' in directory '/usr/local/lib/node_modules/appium/node_modules/appium-xcuitest-driver/WebDriverAgent'
[XCUITest] Unable to start WebDriverAgent: Error: Command 'idevicedate -u 842c6615c76e1d00caf8a010e70feb40ce1c95ba' exited with code 255
[XCUITest] Unable to start WebDriverAgent: Error: Command 'idevicedate -u 842c6615c76e1d00caf8a010e70feb40ce1c95ba' exited with code 255
[XCUITest] Shutting down sub-processes
[debug] [XCUITest] Running ios real device reset flow
[debug] [XCUITest] Resetting simulator
[debug] [iOSLog] Stopping iOS log capture
[MJSONWP] Encountered internal error running command: undefined
[HTTP] <-- POST /wd/hub/session 500 1862 ms - 262 

还有就是 log 开头很多 null 有关系吗 如下

[debug] [MJSONWP] Calling AppiumDriver.createSession() with args: [{"deviceName":"iPhone 6s","udid":"842c6615c76e1d00caf8a010e70feb40ce1c95ba","automationName":"XCUITest","platformVersion":"9.3.5","platformName":"ios","bundleId":"com.xxxxxxxxxxxxx.test"},{},null,null,null,null,null,null,null,null,null,null,null,null,null]