Implement error handling for save data unserialization.

[EliteMasterEric]

FlxSave.status will now be set to ERROR(e) in the event that haxe.Unserializer encounters an error.

Partially resolves #3269 (still requires the application to query for an error and resolve the issue itself and I'm not sure of any good way to fix issues with the Unserializer).

[Geokureli]

can i get an example of how to trigger this issue?

[Beelijah]

geokureli you can download versions v0.5.2 and v0.5.0 of friday night funkin (game based in haxeflixel), and you can run v0.5.2.

then, complete a song in 0.5.2. now launch 0.5.0.

boom, save data wiped. gone. forever. overwritten. destroyed.

[Geokureli]

Is there a simpler way to reproduce this? Preferably a small test state, that manually saves outdated, raw serialized data, and then loads it via FlxSave:

1. I'm going to have to test this dozens of times
2. I want to test this via breakpoints and debugging tools, not by watching a game crash
3. I'd like to make a unit test that checks for it
4. I want to better understand what causes it

[Beelijah]

oh idk then, my brain smaller than a lays potato chip

[AbnormalPoof]

Is there a simpler way to reproduce this? Preferably a small test state, that manually saves outdated, raw serialized data, and then loads it via FlxSave:

1. I'm going to have to test this dozens of times
2. I want to test this via breakpoints and debugging tools, not by watching a game crash
3. I'd like to make a unit test that checks for it
4. I want to better understand what causes it

AFAIK The issue Friday Night Funkin’ had in FunkinCrew/Funkin#3679 was due to an enum value that wasn’t present in older versions. So I think it’s simple as making a save with an enum value, and then recompiling the project without said enum value. (The save data will likely fail to parse since the project can’t find the enum that’s referred to in the save data)

[Geokureli]

Closing, merged #3286

Thanks for laying the foundation, here