I have a custom sized door in my house that suffered damage from dripping condensation in the area. The poplar door had a damaged areas plus some cracks. I’ll show you how I fixed the door in the following photos.

Here you can see the damaged door with various cracks.
Using a circular saw and a rail I cut out some of the damaged wood.
Here is the piece that I cut out.
I also cut into the other cracks to make them large enough to accept an epoxy wood filler.
I used Minwax wood filler. This is an epoxy product that cures very quickly. I mixed the two agents a little at a time so I would have a useable product.
I sanded down the filled areas. You can see the large chip that I cut out.
Painting on a primer coat.
Now ready for painting. No one will ever know that this door was ever damaged.