Firmware File Sanity Check Before Flashing?

[Yonkiman]

I just installed DuetWiFiFirmware-1.18beta2.bin. Except I didn't. In github, instead of clicking on the "DuetWiFiFirmware-1.18beta2.bin" link, and then clicking "Download", I absentmindedly right clicked on the "DuetWiFiFirmware-1.18beta2.bin" link, and saved that```
file instead. I then uploaded the file via the Web Interface, told it to flash this new firmware, so it flashed the HTML file and bricked my DuetWifi.

I got everything working again thanks to Mr. Crocker's excellent documentation, but was a bit surprised that this sort of mistake could happen. Would like to suggest adding a sanity check somewhere, but I'm not sure if that would fall under dc42 or chrishamm...

[dc42]

It's already on the wish list, and I'll escalate the priority.