add checks for grfX handlers to prevent divide-by-zero with slimproto (…

…#424)

Thank you!

Fix crash from led_vu when no display - release

Fix crash from led_vu when no display - release

Fix crash from led_vu when no display - release

Fix crash from led_vu when no display - release

Fix crash from led_vu when no display - release

Merge branch 'master-v4.3' of https://github.com/sle118/squeezelite-e…

…sp32 into master-v4.3

Merge branch 'master-v4.3' of https://github.com/sle118/squeezelite-e…

…sp32 into master-v4.3

Merge branch 'master-v4.3' of https://github.com/sle118/squeezelite-e…

…sp32 into master-v4.3

Merge branch 'master-v4.3' of https://github.com/sle118/squeezelite-e…

…sp32 into master-v4.3