That error is because events can grow "stale" when it comes to referencing animation ID's in the Database. Most likely you had events pointing to animation ID's that have since been removed (the max number of animations shortened). That's the only way I could reproduce it so far at least :)
I've added a check for this in the latest master build (https://raw.githubusercontent.com/TorD/rmmv-preload-manager/master/TDDP_PreloadManager.js). It'll now check the validity of the returned animation object and print a warning and skip it if it's not valid.
Update: Here's a preview of a simple loading screen I made using the public methods of the Preload Manager. I plan to release a configurable plugin addon for showing loading indicators like this:
I've added a check for this in the latest master build (https://raw.githubusercontent.com/TorD/rmmv-preload-manager/master/TDDP_PreloadManager.js). It'll now check the validity of the returned animation object and print a warning and skip it if it's not valid.
Update: Here's a preview of a simple loading screen I made using the public methods of the Preload Manager. I plan to release a configurable plugin addon for showing loading indicators like this:
WOW!!! That plugin would be awesome and extremely useful!!! I hope we can make customizable and animated loading screen! *__*

