Have you startzed a new game after reordering them?
Whenever you either reorder plugins or turn them off/on, that makes the older savefiles incompatible because part of the plugin data gets stored into them. And then continuing a game that contains that old data can result in a lot of "undefined" errors, simply because the plugin that defined that data has been turned off or is no longer at the expected position.
That said, here is some background info so that you better understand why that error has us asking and doublechecking your project version:
"height" is a property that was introduced in 1.4.0 or 1.5.0 or so to make a lot of things easier - it didn't exist in older versions.
And if a plugin then tried to use this property with older core files, they gave this error because "height" was not yet defined in them.
So whenever that error message came up previously, it was always someone using current plugin versions with a core version 1.3.0 or older.
You are literally the very first case with this error message that has a newer core version.
And I can now only think of two remaining options why you get this error:
1) you have always tested with an old savegame that contained the data of the old core-structure
2) your last update was incomplete and only some of the core files were updated to 1.6.1 (including the rpg_core.js) while others failed to update correctly and are still at pre-1.4
In the second case make a backup and try to update that to 1.6.2 and see if that corrects such a failed update.
I just thought of a third possibility. Can you go into your project folder and check if it contains a www folder?
Hopefully not because that folder should only exist in a deployed version, never in a project directory - but it would redirect all tests and we would have looked at the wrong folders if that is the case.
If you have a www folder inside your project directory, then delete it and replace your package.json file in the project directory with one from a new project - a failed deployment will create the ww folder and exchange the packages file with the wrong one for the project directory.