that is where Scamp puts a gas smaller heater. the top of the smaller heater lines up with the top of the brown door.
I hope your previous install did not cut into the
fiberglass, when you take out the heater the opening should not be open higher than the brown door.
We did not get the heater and have two skinny doors. There is wood glassed in above the doors, between the doors, and on the side of the doors. If your top glassed in wood has been compromised you might want to stiffen that up.
We have considered cutting out the space between the two doors to have one larger door. But, we would still have the stiffness above and to the sides.
We only carry a small electric cube heater. If there is no electricity we try not to be out below 40 degrees because we are old folks. Really don't want a gas heater. Just heating some water on the stove warms the little Scamp up.
Also make sure the PO did not remove the black iron supports between the sink and upper cabinets. They are necessary. Replace with something visually nicer but keep support there.
Nancy