I have an Air Purifier and one of the entities is a fan, of course.
The fan has speeds from 1 to 5, but NOT zero; the fan cannot be turned off.
Also, the fan entity does not include a power switch. (There is another entity for a power switch that turns everything off; fan, electronics, light, etc.)
But HA seems to think all fans have power switches and all fans have speeds that go to zero.
The result is that when I add the entity to a card, I get an object with a power button … that generates an error if inadvertently pressed. And I get a slider that runs from 100% to 0% … and generates an error if inadvertently slid to 0.
It’s not a problem, it’s just inelegant; it feels … unfinished.
If an entity doesn’t have a button, an error generating button should not be displayed.
And if an entity with selections does not have a “zero” option, it should not be possible to select an error generating “zero”.