TypeError: this.props.value?.get is not a function

**Describe the bug**

**To Reproduce**

**Expected behavior**

**Screenshots**

**Applicable Versions:**
- Decap CMS version: `decap-cms@3.12.2`
- Git provider: `git-gateway`
- Browser version: `Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/147.0.0.0 Safari/537.36`

**CMS configuration**
```
backend:
name: git-gateway
branch: main
media_folder: images
public_folder: /images
collections:
- name: pages
label: Pages
files:
- file: index.html
label: Main Website Content
name: home
fields:
- label: Website Code
name: body
widget: code
defaultLanguage: html
publish: true
type: file_based_collection
sortable_fields:
- field: commit_date
- field: commit_author
view_filters: []
view_groups: []
publish_mode: simple
slug:
encoding: unicode
clean_accents: false
sanitize_replacement: "-"
isFetching: false
error: null

```

**Additional context**