[BUG] Dynamic mode generate 404 errors

### **Describe the bug**

Darkreader is ON with Dynamic mode under Firefox 82 (Archlinux).

Works great but when I go to my Nextcloud website it generates 404 errors :

```
[18/Nov/2020:10:40:23 +0100] "GET /svg/spreed/app-dark?color=000&v=1 HTTP/1.1" 404 10785 "-" "Mozilla/5.0 (X11; Linux x86_64; rv:82.0) Gecko/20100101 Firefox/82.0"
[18/Nov/2020:10:40:23 +0100] "GET /svg/spreed/app?color=000&v=1 HTTP/1.1" 404 10785 "-" "Mozilla/5.0 (X11; Linux x86_64; rv:82.0) Gecko/20100101 Firefox/82.0"
[18/Nov/2020:10:40:23 +0100] "GET /svg/guests/app?color=000&v=1 HTTP/1.1" 404 10785 "-" "Mozilla/5.0 (X11; Linux x86_64; rv:82.0) Gecko/20100101 Firefox/82.0"
[18/Nov/2020:10:40:23 +0100] "GET /svg/circles/circles?color=000&v=3 HTTP/1.1" 404 10785 "-" "Mozilla/5.0 (X11; Linux x86_64; rv:82.0) Gecko/20100101 Firefox/82.0"
```

### **Steps to reproduce**

- Install Nextcloud (nextcloud.com) on your server with required stuff (web server, php, etc.)
- Make it working, create an account
- Login to it with Darkreader activated (dynamic mode)
- Look at your webserver logs, 404 erros

### **Expected behavior**

No 404 errors when changing Darkreader parameter

### **Actual behavior**

404 errors when changing darkreader parameters (brightness, contrast, etc.) in dynamic mode

### **System Information:**

- OS: Manjaro Linux
- Browser: Firefox 82
- Dark Reader version: 4.9.23