Error while restoring a save on mobile

[AbsoluteJuicer]

I've been playing Flexible Survival on mobile for a long time and it was fine. I started encountering this problem since ~2019 (I forgot) and only recently have I started to familiarize with Github to report this issue.

iOS App Name and Version: Frotz (1.8.8) (iOS versions did not prevent the problem from occurring, earlier Frotz versions also have this problem)
Story File Version: August 2023 (earlier versions also had this problem, unless it's really early, like 2016 versions)
Error Message: ***fatal error: Heap block summary is out of order.*** ***fatal error: Heap block summary is out of order.*** (note: this message is repeated as shown)

How to crash the game:
In short: Restoring a save will trigger it (click [Restore] -> click a savefile -> then the game will crash, showing the error message)
Full method: (start a new game) -> when you are in the bunker, click [import progress] -> after the progress is successfully imported, save game by clicking [save] -> now anytime the game will crash when restoring a save, while undoing is fine