When one of the devices is offline, Exception has been throwed

[nkligang]

When one of the devices is offline, Exception has been throwed, get the device failed, I think this is not well designed, Can you fix it?

[DavidREntwistle]

This looks related to "Exception in thread "pool-4-thread-1" java.io.IOException: Command failed (host:transport:emulator-5554): device 'emulator-5554' not found" - @nkligang is this the same exception you've noticed?