Order of operations (erase, check file, write)

[galmok]

I just tried to flash using this tool, and there is a way to make the experience a bit better.

Currently the order of operations is erase, validate file, flash.

But this order is much better: validate, erase, flash.

Reason being is that if you provide the wrong file, or the file is bad, you are right now left with a device without a firmware. Using the suggested procedure, the validity of the file is checked before the device is erased. An early stop would preserve the existing firmware if the file is bad.

[JelmerT]

@galmok that makes a lot of sense, feel free to submit a PR!