NetworkError when attempting to fetch resource.

### Which version of floccus are you using?

5.9.1

### How many bookmarks do you have, roughly?

400

### Are you using other means to sync bookmarks in parallel to floccus?

No

### Sync method

WebDAV

### Which browser are you using? In case you are using the phone App, specify the Android or iOS version and device please.

Firefox

### Which version of Nextcloud Bookmarks are you using? (if relevant)

_No response_

### Which version of Nextcloud? (if relevant)

_No response_

### What kind of WebDAV server are you using? (if relevant)

SFTPGo 2.7.99-dev in Docker

### Describe the Bug

I was using floccus (With Firefox browser) for a long time, but it stopped to work 2 weeks ago or so.
Floccus gave me this error NetworkError when attempting to fetch resource. I deleted my profile and want to create a new one, but it gives me the same error.

WebDav is reachable from PC
```
curl http://192.168.36.3:34281/dav2025
Authentication error: no credential provided

```

At the same time, Android version work fine with the same config.

### Expected Behavior

Floccus should connect with WebDav server without issues.

### To Reproduce

Install Firefox
Add Floccus plugin
Try to connect to WebDav

### Debug log provided

- [ ] I have provided a debug log file