Misleading error message if no pdf viewer is installed

### ⚠️ Before posting ⚠️

- [x] This is a **bug**, not a question or an enhancement.
- [x] I've [searched for similar issues](https://github.com/nextcloud/android/issues) and didn't find a duplicate.
- [x] I've written a clear and descriptive title for this issue, not just "Bug" or "Crash".
- [x] I agree to follow Nextcloud's [Code of Conduct](https://nextcloud.com/contribute/code-of-conduct/).

### Steps to reproduce

1. without a pdf reader installed (or pdf not associated with any application)
2. open a pdf file e.g. from Nextcloud Talk

### Expected behaviour

Some error message, that no pdf viewer is installed (e.g. like K-9 mail which finally helped me to find out the actual problem)

### Actual behaviour

Nextcloud Client shows a completely misleading 204 HTTP error

Once a pdf reader was installed, e.g. MuPDF, the PDF was opened successfully

### Android version

unknown

### Device brand and model

Samsung

### Stock or custom OS?

Stock

### Nextcloud android app version

latest

### Nextcloud server version

31

### Using a reverse proxy?

Yes

### Android logs

204 HTTP error

### Server error logs

```bash

```

### Additional information

_No response_