onCreateEditFields values not submitted because of JavaScript errors

[lorenzulrich]

Bug Report

Prerequisites

• Can you reproduce the problem on TYPO3 v10.4 LTS
• Did you perform a cursory search to see if your bug or feature is already reported?

Description

I am using YAML mode.

If onCreateEditFields are defined, e.g. the page title, the fields are rendered properly.

However, on displaying the form with the fields to edit, a JS error appears in the console:

Uncaught TypeError: Cannot read property 'addEventListener' of undefined
    at Object.FormEngine.initializeEvents (VM7620 FormEngine.js:603)
    at HTMLDocument.<anonymous> (VM7620 FormEngine.js:1361)
    at mightThrow (VM7626 jquery.js:3557)
    at process (VM7626 jquery.js:3625)

This has the effect that the field value is not copied to the according hidden field and therefore the value is not submitted.

Steps to Reproduce

1. Create a site configuration with an onCreateEditFields for the page, e.g. title.
2. Use this page template to create a new page.
3. Fill in the title field and click "Save New Page"

Expected behavior: The page is saved and the title value entered is used.

Actual behavior: The page is saved, but the title value remains empty.

Versions

1.2.0