Basically, when I added the gallery to the latest version (V4-V7), a lot of bugs started popping up that I didn't notice. Bugs I can't really sell the game with. The problem is that of the two error messages that have been reported so far, I can't reproduce either of them.
So, I have a favour to ask of those who have already purchased the game, if you'd like to help me out.
Download this version, and either do a run-through from scratch or just use it with a previous save and tell me what bugs you encounter. Any error messages, and especially CG or enemy gallery progress being reset (As you encounter enemies, they should appear in the enemy gallery room). Some errors may occur by restarting the game. (Note that you can also change your progress through editing the prog.dll file)
Hopefully I can fix these issues soon and release it on DLsite sometime tomorrow, so I can finally be done with Eroico and start the next game.
Buying the game
If you don't care about the enemy gallery (the CG gallery is still there) and want to buy the full game before I finish these bug fixes, you can go back a few posts to V3, which doesn't have the bugs I'm referring to here.