Well, the error looks like it is having trouble canceling out of the Display window back to the List window, not canceling out of the reputation scene, do you have any reputations set up?
Viewing post in [CGMZ] Reputations for RPG Maker MZ comments
I'm not too sure, as I am unable to reproduce the problem in my test project. If you want, you could send me a sample project with just [CGMZ] plugins installed that has the problem so I can take a look at it. You can send me a DM over discord with a link to download the project with the issue.
One thing you could try is to paste this into the bottom of the plugin's .js file, but it might just make the error occur at a different place:
CGMZ_Window_ReputationList.prototype.item = function() {
return (this._data) ? this._data[this.index()] : null;
};