Deleting option of Grid Field in form with multiple language makes form builder not render

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 7.1.0 M1, Master
• Fix Version/s: 7.1.0 M2, 7.1.X, Master
• Component/s: Forms
• Labels:
  • QA-AUTOMATION
  • forms.liferay.com
  • fw_test_poshi
• Fix Priority: 5
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/56468

Steps to reproduce:

1. Add a Grid field with 3 rows and 3 columns at default locale (English)
2. Add a translation (PT, for example)
3. Translate the grid field options
4. Save form
5. Delete one row
6. Save form

Expected result:
Form should be rendered and Grid field should have only two rows in all translations.

Actual result:
Form keeps loading forever and JS console error is thrown:

grid_field.js?browserId=other&minifierType=&languageId=en_US&b=7100&t=1520829818932:99 Uncaught (in promise) TypeError: Cannot read property 'en_US' of null
    at component._getLocalizedLabel (grid_field.js?browserId=other&minifierType=&languageId=en_US&b=7100&t=1520829818932:99)
    at grid_field.js?browserId=other&minifierType=&languageId=en_US&b=7100&t=1520829818932:107
    at Array.forEach (<anonymous>)
    at component._mapItemsLabels (grid_field.js?browserId=other&minifierType=&languageId=en_US&b=7100&t=1520829818932:105)
    at component._setRows (grid_field.js?browserId=other&minifierType=&languageId=en_US&b=7100&t=1520829818932:149)
    at component._setAttrVal (attribute-core.js:851)
    at component._setAttr (attribute-core.js:657)
    at component.set (attribute-observable.js:69)
    at component.addAttr (attribute-core.js:455)
    at component._addLazyAttr (attribute-core.js:530)