Can not nest Text field inside Separator field

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: Master
• Fix Version/s: 7.4.13 DXP GA1, Master
• Component/s: Data Engine
• Labels:
  • QA-AUTOMATION
  • migration_to_dataengine
• Epic/Theme:
  • Old_Form_Builder_Renderer_Replacement
• Fix Priority: 4
• Sprint: Data_Engine_7.4_04
• Git Pull Request: https://github.com/marcosapmf/liferay-portal/pull/276
• QA Test Name:
  • LocalFile.ExportImport#ExportImportWebcontentWithRepeatField
• QA Test Score: 3

Step to reproduce:

1. Product Menu > Content & Data > Web Content > Structures tab
2. Add a new structure
3. Add a Separator field into form
4. Drag and drop a Text field inside the Separator field

Expected Results:
The Text field should be nested inside the Separator field.

Actual Results:
The following error is shown in browser console:

Reproduced on:
Tomcat 9.0.37 + MySQL 5.7. Portal master GIT ID: 58c93cc3229fee3b08c1076d1096f5ed567f5ea5.