As David posted, the switch “should not be inside a closet”.
However, are you the AHJ?
Does the switch function correctly?
Is the switch cover plate in place (even though it says oil burner)?
I recommended that you identify the location of the switch. The location of the switch is where it was the day the house was built. There is no requirement to upgrade pre-existing conditions to current requirements. The fact that the furnace is propane fired versus oil fired really has no bearing on the switch plate cover! It obviously goes to the furnace (of some sort). At least it’s identified as such.
Does this condition meet any of the following criteria:
This component does not function as intended.
This condition adversely affects the habitability of the dwelling.
This condition requires repair.
This condition requires subsequent observation.
This condition warrants further investigation by a specialist.
If so, report it as such.