Here is the initial code for the custom component under v5.x:

import { Formio } from '@formio/react';
const FieldComponent = Formio.Components.components.field;

After upgrading to 6.x, it fails with the console log:

Uncaught TypeError: Cannot read properties of undefined (reading 'Components') at SummaryInput.js:2:31

The IDE (Webstorm) also reports that it "cannot resolve symbol 'Formio'"

Where is the documentation that supports this? All documentation for custom components assumes vanilla JS, nothing about integration with React (or Angular, I suppose).