json_schema.contrib generate crash by stack overflow 

1. run this 
```bash
pkl eval package://pkg.pkl-lang.org/pkl-pantry/org.json_schema.contrib@1.1.1#/generate.pkl \
                          -m . \
                          -p source="https://json.schemastore.org/github-workflow.json"
```

2. got this
```
–– Pkl Error ––
A stack overflow occurred.
```