TypeError: t.get is not a function

**Describe the bug**

Getting `t.get is not a function at new npe` when opening up a collection. I am not sure if this is error happens because of my incorect setup/config, of this is a genuine issue.

```
Details
TypeError: t.get is not a function at new npe (https://unpkg.com/decap-cms@%5E3.0.0/dist/decap-cms.js:464:37972) at js (https://unpkg.com/decap-cms@%5E3.0.0/dist/decap-cms.js:5:721919) at Xs (https://unpkg.com/decap-cms@%5E3.0.0/dist/decap-cms.js:5:731984) at Xu (https://unpkg.com/decap-cms@%5E3.0.0/dist/decap-cms.js:5:769131) at Ku (https://unpkg.com/decap-cms@%5E3.0.0/dist/decap-cms.js:5:769060) at Gu (https://unpkg.com/decap-cms@%5E3.0.0/dist/decap-cms.js:5:768902) at ju (https://unpkg.com/decap-cms@%5E3.0.0/dist/decap-cms.js:5:765711) at Sc (https://unpkg.com/decap-cms@%5E3.0.0/dist/decap-cms.js:5:780026) at MessagePort.A (https://unpkg.com/decap-cms@%5E3.0.0/dist/decap-cms.js:2:1721401)
```

**To Reproduce**

Request access for https://a-plan-b.netlify.app/admin/, then click on the only collection

**Expected behavior**

No error shown

**Screenshots**

**Applicable Versions:**
- Decap CMS version: `decap-cms@3.9.0`
- Git provider: `git-gateway`
- Browser version: `Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36`

**CMS configuration**
```
backend:
name: git-gateway
branch: main
media_folder: images/uploads
public_folder: /images/uploads
collections:
- name: pages
label: Pages
files:
- file: PlanasB_landing_page.html
label: Planas B Landing Page 1
name: planasb_landing_page_1
editor:
preview: false
fields:
- label: HTML
name: body
widget: code
default_language: html
publish: true
type: file_based_collection
sortable_fields:
- commit_date
- commit_author
view_filters: []
view_groups: []
publish_mode: simple
slug:
encoding: unicode
clean_accents: false
sanitize_replacement: "-"
isFetching: false
error: null

```

**Additional context**

`Index.html` loads `decap-cms@^3.0.0` and `netlify-identity-widget`.

```

Content Manager

```

Start with the CMS configuration and index.html, then reproduce the error by opening the only collection at the provided admin URL. Inspect the decap-cms.js stack location around 464:37972 and compare the file-based collection settings with the expected collection-opening behavior. Done means the collection opens without the TypeError.

Written by the indexing model from the issue text.