That makes no sense to me. Why not have an on light instead? If the light is on, and the device is operating as expected, that’s good. If the light is off then it has no power or it’s broken. If the light is on and nothing is happening, it’s broken.
If the light is going to be annoying when the device is on, then turn it off after a few seconds.
I don’t know. I’ll look it up.
https://www.google.com/search?q=why+are+raisins+toxic+to+dogs+and+not+humans