Handle situation where a webgl context could not be created

[remcoder]

Notify the user of this.

see https://app.logrocket.com/x64tmd/gcode-preview-demo/s/6-0196f284-39c6-7bcd-863d-5b16a517b717/0?dashboardID=logrocket-analytics&fromTab=&interval=1d&persistForm=true&range=1M&rangeEnd=1747895734762&rangeStart=1745303734762

also, while at it, notify when webgl is not supported at all.

And where I said 'webgl' possibly replace that with 'webgl2'.

bonus for adding documentation about compatibility