Substances without names

There are eight substances without names.

``` rq
PREFIX : <https://agriculture.ld.admin.ch/plant-protection/>
PREFIX schema: <http://schema.org/>
SELECT DISTINCT ?substance
WHERE {
  ?substance a :Substance .
  FILTER NOT EXISTS {
    ?substance schema:name ?name .
  }
}
```

Although they seem to exist in the data. There must be some bug in the integration.