Avoid Crashes when a Block/Disk Device Disappears

I observed on one system that if a Device gets removed it can cause the Script to Crash (I'm currently playing around with LOOP Devices and if `/dev/loopX` disappears, the Script can Crash).

Not sure if this also happens in the current Master Version or if that's something that was limited to a previous Version.

Maybe the Devices are not scanned at each Iteration ? Unsure ?