Form Builder corrupted existing fields

We added a few fields to “Item List” and they appeared at the end of “Manufacturing” tab screen. Later we decided to create a new tab and moved the new fields there - using “Try the new form builder” option. Now we are getting JS console error when loading the page and trying to add New Item in the Item List screen.

When loading Item List
DevTools failed to load source map: Could not load content for http://awsdev4.innoterra.co.in:8000/app/file_uploader.bundle.UERHWJNK.js.map: Unexpected token ‘<’, "<!DOCTYPE "… is not valid JSON

When adding new Item
caught (in promise) TypeError: Cannot read properties of undefined (reading ‘doctype’)
at new Tab (tab.js:6:27)
at Dialog.make_tab (layout.js:314:13)
at layout.js:169:11
at Array.forEach ()
at Dialog.render (layout.js:153:10)
at Dialog.make (layout.js:39:8)
at Dialog.make (field_group.js:22:10)
at Dialog.make (dialog.js:50:9)
at new Dialog (dialog.js:17:8)
at ItemQuickEntryForm.render_dialog (quick_entry.js:126:17)
Tab @ tab.js:6
make_tab @ layout.js:314
(anonymous) @ layout.js:169
render @ layout.js:153
make @ layout.js:39
make @ field_group.js:22
make @ dialog.js:50
Dialog @ dialog.js:17
render_dialog @ quick_entry.js:126
render_dialog @ item_quick_entry.js:12
(anonymous) @ quick_entry.js:42
with_doctype @ model.js:232
(anonymous) @ quick_entry.js:38
setup @ quick_entry.js:37
frappe.ui.form.make_quick_entry @ quick_entry.js:24
(anonymous) @ create_new.js:367
with_doctype @ model.js:232
(anonymous) @ create_new.js:362
frappe.new_doc @ create_new.js:358
make_new_doc @ list_view.js:286
(anonymous) @ list_view.js:268
(anonymous) @ page.js:268
dispatch @ jquery.js:5430
elemData.handle @ jquery.js:5234
Promise.then (async)
(anonymous) @ create_new.js:368
with_doctype @ model.js:232
(anonymous) @ create_new.js:362
frappe.new_doc @ create_new.js:358
make_new_doc @ list_view.js:286
(anonymous) @ list_view.js:268
(anonymous) @ page.js:268
dispatch @ jquery.js:5430
elemData.handle @ jquery.js:5234