A 432x110568 image (The tilesheet for Deep Dark Crater) was unable to be loaded in the map editor. The bitmap image it is being saved to is simply too large. Need to come up with an optimization for this.
Line of interest: https://github.com/RogueCollab/RogueEssence/blob/66ef2f2e6c6d0f27c849ea8bdafe410f4759564a/RogueEssence.Editor.Avalonia/DevGraphicsManager.cs#L150
A potential solution would be to break up the image into an array of smaller ones. However, this will require the tileset viewer code to be changed to accommodate the piecewise images.