[VSCRIPT] CScriptKeyValues instances not being saved

[JillCrungus]

Describe the bug

When saving the game, CScriptKeyValues instances in VScripts are not saved. An error is printed in the console when saving and then when loading the keyvalues instance will be null;

Steps to reproduce

1. Create a script that creates or loads a CScriptKeyValues instance
2. Save the game, observe an error in the console
3. Load the game. The instance will now be null.

Expected behavior

CScriptKeyValues instances should be saved and preserved when loading games

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Additional context

Before loading save:

Error given when saving:

After loading save:

[Blixibon]

I've noticed this issue extends to other C++ instances as well, like matrix3x4_t.

However, after looking into it further, it would appear that this is due to non-entity C++ instances in general (including CScriptKeyValues) not having default save/restore handling in the first place. VScript assumes that instances are saved in unrelated areas, using IDs to link the unrelated save/restore code with VScript. This is how entity instances are restored. However, instances like CScriptKeyvalues are constructed within the script and therefore don't have any data being stored elsewhere.

Fixing this would not be a simple task, and I'm inclined to believe that instances constructed in this way were never meant to be saved in the first place.

With that in mind, I think all that could really be done about this issue is to just avoid putting CScriptKeyValues instances in a position where they would be saved. Fortunately, there are some new TableToSubKeys() and SubKeysToTable() functions in CScriptKeyValues which allow them to be converted to actual Squirrel tables, which can be saved. I would recommend using those when save/restore functionality is needed.

[JillCrungus]

I've noticed this issue extends to other C++ instances as well, like matrix3x4_t.

However, after looking into it further, it would appear that this is due to non-entity C++ instances in general (including CScriptKeyValues) not having default save/restore handling in the first place. VScript assumes that instances are saved in unrelated areas, using IDs to link the unrelated save/restore code with VScript. This is how entity instances are restored. However, instances like CScriptKeyvalues are constructed within the script and therefore don't have any data being stored elsewhere.

Fixing this would not be a simple task, and I'm inclined to believe that instances constructed in this way were never meant to be saved in the first place.

With that in mind, I think all that could really be done about this issue is to just avoid putting CScriptKeyValues instances in a position where they would be saved. Fortunately, there are some new TableToSubKeys() and SubKeysToTable() functions in CScriptKeyValues which allow them to be converted to actual Squirrel tables, which can be saved. I would recommend using those when save/restore functionality is needed.

While it does feel a little awkward to need that intermediate step, I think that in the end using CScriptKeyValues just for for I/O and construction of K/Vs and converting everything to and from native Squirrel types does indeed feel like a more "right" way to do things. At any rate, it's certainly better than your scripts completely breaking in save/load just because you wanted to use keyvalues for data that'd need to persist.