### Setup and configuration

- MW version:
- PHP version:
- DB (MySQL etc.):
- SMW version:
- SG version:
- Lingo version:

### Issue

Produces a [stack trace](https://www.semantic-mediawiki.org/wiki/Help:Identifying_bugs) and outputs:

```
```

Steps to reproduce the observation (recommendation is to use the [sandbox](https://sandbox.semantic-mediawiki.org)):