Bootstrap-4 theme does not render array with different item types

[rkeulemans]

Prerequisites

• I have read the documentation;
• In the case of a bug report, I understand that providing a SSCCE example is tremendously useful to the maintainers.
• Ideally, I'm providing a sample JSFiddle or a shared playground link demonstrating the issue. Codesandbox Here

Description

The bootstrap-4 theme does not render when using this schema, while the core does this perfectly fine (see Codesandbox)

{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "title": "Name Registration Form",
  "type": "object",
  "required": [
      "full_name"
  ],
  "properties": {
      "full_name": {
          "title": "Full Name",
          "description": "Please provide your full name",
          "type": "array",
          "items": [
              {
                  "type": "string"
              },
              {
                  "type": "string"
              }
          ],
          "maxItems": 2,
          "minItems": 2
      }
  }
}

Steps to Reproduce

Run Codesandbox.

Expected behavior

Renders the schema in the UI.

Actual behavior

Does not render schema and presents an error:

Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined. You likely forgot to export your component from the file it's defined in, or you might have mixed up default and named imports.

Check the render method of `ArrayFieldDescription`.

Version

You can usually get this information in your package.json or in the file URL if you're using the unpkg one:

  "dependencies": {
    "@rjsf/core": "4.1.0",
    "@rjsf/bootstrap-4": "4.1.0",
    "react-bootstrap": "1.6.4",
    "react": "17.0.2",
    "react-dom": "17.0.2",
    "react-scripts": "4.0.3"
  },

[heath-freenome]

Fixed in the v5 beta, see the 5.x migration guide