[Bug] EV3 firmware installation sends bad status values

[laurensvalk]

During EV3 firmware installation, variations of the following were observed on multiple operating systems from different users. Including Windows and Ubuntu. For some users this does not happen.

Error: EV3 reply status error: 126 for command 246
    at sendCommand (http://localhost:3000/static/js/bundle.js:22082:26)
    at sendCommand.next (<anonymous>)
    at handleFlashEV3 (http://localhost:3000/static/js/bundle.js:22086:42)
    at handleFlashEV3.next (<anonymous>)
    at next (http://localhost:3000/static/js/bundle.js:74363:29)
    at currCb (http://localhost:3000/static/js/bundle.js:74447:7)
    at chCbAtKey (http://localhost:3000/static/js/bundle.js:73961:9)
    at currCb (http://localhost:3000/static/js/bundle.js:74447:7)
    at takeCb (http://localhost:3000/static/js/bundle.js:73793:5)
    at Object.put (http://localhost:3000/static/js/bundle.js:73522:5)

To reproduce, go to https://labs.pybricks.com/ and attempt EV3 installation or recovery. For installation, you'll need to provide your own ZIP file since there isn't one included yet. If you don't have a firmware zip file, just try recovery instead.