Ultima Underworld 1 "Underworld internal error. Problems in object list" bug source found and instructions on how to prevent it and fix it

EDIT: I have released a webpage that fixes this bug. [Link](https://karlclinckspoor.github.io/UltimaUnderworldSaveFixer/)

The decomp+port recently released by u/abedegno [(reddit post here)](https://www.reddit.com/r/Ultima/comments/1x1tu3e/ultima_underworld_1_2_decompiled_to_source_that/) has shed some light in this infamous bug. I've even written about how to fix it [here](https://www.reddit.com/user/PraecorLoth970/comments/14bzx4y/solving_underworld_internal_error_problems_in/), but it's a complicated and long process. Here's what they found out:

> Thanks for the saves. They pinned this one down, and it's a bug in the original game that the port reproduces exactly.

> When you ask for part of a stack on the floor ("Move how many?") and the game then says it's too heavy to pick up, the game has already made a copy for the part you asked for. It puts the amount back on the stack but never frees the copy, so one object is left over, belonging to nothing. The next time you change level or restore, the game's own check counts 767 objects where there should be 768 and prints "Problems in object list". Both your saves have exactly one such object: arrows in the first (13 minus the 5 asked for) and coins in the second (8 minus 1). Both characters were close to their weight limit. I reproduced it from scratch in DOS and in the port, and the leftover object is the same in both.

> It's harmless. Nothing you own is lost, because the real stack keeps its full count. It isn't related to the bug that deletes key items. And destroying items can't clear the message, because a destroyed item still counts towards the 768. Each leak does use up one of the level's object slots for good, but your levels have more than 200 to spare.

> The next release (UW1 1.0.2) adds an optional gameplay enhancement, tidy-objects. It frees the copy, as UW2 already does, and when the check fails on arriving at a level it puts the leftover objects back, so your existing saves heal themselves. It's off by default, like every enhancement, because the original game behaves this way. Until then, the message can be ignored. To avoid new leaks, don't split a floor stack when you're near your weight limit.

So there you have it. It's a relatively harmless bug, and by using your save in the port with the new option, you can fix it easily. Since many people have asked around about this, I've deemed it useful to share.

Note that this isn't the infamous bug about losing items in levels with too many. That's still a hard cap because of how the save game file is structured. This structure also causes a rare bug in UW1 where you can crash your game if you load a map edited in a very specific way. Also fixed in the port.