CONSTRUCT can return with bad triple terms

### Version

6.1.0

### What happened?

CONSTRUCT can return triple terms with literals in the subject position of the triple term.

```sparql
CONSTRUCT {
    :tt4 :p <<( 123 :c2 :c3 )>> .
} WHERE {}
```
returns a triple.

### Relevant output and stacktrace

```shell

```

### Are you interested in making a pull request?

Yes