@Venex When you start a new game, objects like $gameParty are initialized with certain properties. Many plugins - this included - add their own code to the initialize function. This plugin adds four additional properties to the $gameParty object on initialization. (lines 255ff. in the plugin file, if you want to look at them yourself)
When you load a previous save, the objects are not initialized again. I'll try to explain what happened here to show why that is a problem:
My plugin modifies the isBattleMember function of Game_Actor. The modified function looks - among other things - for a property _LB_battleMembers in the $gameParty object (it checks an actor is contained in that list). This property is added by my plugin when the $gameParty object is initialized. Since you did not start a new game, but loaded a save file from a time when the plugin was not yet installed, the $gameParty object in that save file does not have the property. So when the isBattleMember function is called, the program tries to check if a property that does not exist (i.e. that is "undefined") "contains" something. That doesn't work; hence the error. And similar errors occur with other plugins that save their own properties in game objects.
In this case, I can tell you which script calls you need to run to repair the missed initialization:
Code:
$gameParty._LB_battleMembers = [];
$gameParty._LB_partyMembers = [];
$gameParty._LB_summon = null;
$gameParty._LB_summonId = 0;
It's not quite as easy with more complex plugins, especially when the developer is not around and you can't read Javascript well enough to find out what you have to do yourself, or when the error occurs before you can call a script that would fix it. That is why it's good practice to start a new game after adding a new plugin to the project. Most developers create debug NPCs or items to avoid having to replay the entire game from the start each time - simply give the items, equipment and levels that the player should have to them via events and then teleport to the map you want to continue on.
(Apart from all that, there might be compatability problems with my plugin and Yanfly's Actor Party Switch. If you come across any errors, or things not working the way they should, let me know.)
