[IDF-6907] 4. Wrong web page pop up

[ustccw]

Click Flash button and ready to download firmware, but sometimes, without burning, the "ESP Firmware Flashing Status" web page pop up immediately, and shows:

"Flashing of firmware is completed!"

[igrr]

I think I've seen this issue as well, when we fail to download the binary from the server. This should probably be fixed to show some error message instead.