Multi-Form Goal block should not error when selecting form(s) to filter by on WP 5.9

[LMNTL]

User Story

As an admin, I want to assign a Multi-Form Goal block to a specific set of forms so that I can show donation progress across those forms.

Details

After clicking the dropdown under Filters -> Filter by Form, the inspector controls disappear, some JS errors are generated, and the block itself displays "This block has an encountered an error and cannot be previewed". The block appears fine on reload, but setting the form filter again has the same effect.

Only happens on WordPress 5.9, when testing on 5.8.x I couldn't reproduce.

Expected Behavior

A list of forms should appear after clicking the dropdown, and the user should be able to select one or more forms.

Steps to Reproduce

1. Install WordPress 5.9
2. Install latest version of Give
3. Create a new post
4. Add a Multi-Form Goal block to the post
5. Select the progress bar portion of the block and open its settings.
6. Click 'Filters'
7. Click the "Filter by Forms" dropdown

Visuals

Additional Context

System Information

Details

Acceptance Criteria

• [ ] Enable users to select forms for Multi-Form Goals block.
• [ ] Ensure that the block correctly saves the form settings.
• [ ] The Multi-Form Goals block displays appropriately in the front-end and edit view.

[canny[bot]]

This issue has been linked to a Canny post: Forms cannot be selected in Multi-Form Goal Block :tada:

[github-actions[bot]]

This issue is stale because it has been open 45 days with no activity. Remove stale label or comment or this will be closed in 14 additional days.

[kjohnson]

Closing in favor of feedback.