Yuurei: Utterly Bizarre Crash on 2.50.x Tree Builds

[DarkDragon]

Is "smart scrolling" enabled in this quest by any chance?

[ZoriaRPG]

Is "smart scrolling" enabled in this quest by any chance?

I'm not sure. I'll check tomorrow, but based on what Aevin has to say, the problem can't just be related to scrolling:

Well, consider me confused. It isn't my spawn system; I commented out the entire thing and still got the crash. Then, I turned on "view ffc scripts" through the cheat menu, and ... Right before the crash, I saw that it had begun running the script for one of my ghosted enemies; the script 36 listed in the error log.
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There's nothing that should be running that script, and it certainly doesn't run on any of the previous ZC versions. I really don't know what could be causing this. I'm really doing nothing terribly complicated on my end outside of the spawn system, which is now fully disabled. I even searched for every instance of running ffc scripts in my script file, and that particular script is never once called outside of the specific enemy spawning on certain screens. But the enemy doesn't appear on any of those screens, and it's that specific script that causes the crash on any of the other screens, too, none of which have the enemy.
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It seems to me that ZC is just randomly calling this script, then crashing because there's no enemy associated with it.
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Edit: Looking closer frame by frame reveals that as soon as scrolling begins, it calls a series of ffc scripts. I can't see any rhyme or reason to the ones it calls, but they are consistent depending on which screen I scroll to. For example, going right from the start doesn't crash, but going back left runs three separate ffc scripts in the same slot in quick succession, ending with script 36 before the error. However, cheating and going up through the wall runs a different script, then crashes. The other odd thing is that there are gaps before the scripts that cause the crash, as if there are "blank" scripts being called from further down the script list. For example ... My opening screen has a "ContinuePoint" script that runs at screen init. What I see when walking back left onto the screen is this:
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ContinuePoint
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ultimadome ->SandCroc->Earth Elemental (in quick succession)
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These blank slots (totally blank, not actually dotted lines) also happen when walking up through the wall, but the script that causes the crash there is different.
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Not sure what's going on here ...

That seems to indicate that the ffengine is losing its mind, from something. it could be related to the parser changes that @Saffith implemented. I'm only guessing at present, as I need to run some tests, but perhaps if a quest has more than N ffcs loaded into slots, it isn't properly storing the datum. I truly have no out-of-hand explanation for this; which is why I would like anyone else to compile 2.50.x from 4-Dec-16, as I want to rule out some bizarre compiler issue on our end, using the latest gcc via MSYS.

If gcc is mucking something up terribly, then clearly it is not a viable option and this needs to be addressed.