If we enable Live Preview but have no stroke or fill chosen, drawing on canvas shows nothing. Very useful.
What if in this case you make the edge line visible instead, the one we see when we disable Live Preview? 'Graceful degradation' in a sense — take a look at the GIF attached.
It’s even more complicated than this. Imaging white stroke on white canvas :) Formally it’s a color, but practically...
Having an option to have edge always visible can help, but it’d be another option...
Anyway, please do something.