`AttributeError: 'CrateTypeCompiler' object has no attribute 'visit_JSONPATH'`

## Problem

When deriving a CrateDB adapter for LangChain from [langchain-postgres](https://github.com/langchain-ai/langchain-postgres), we are observing this error when invoking a test case.

```
pytest -vvv -k "test_cratedb_with_metadata_filters_2 and filter10"
```

```python
self = JSONPATH(), visitor =
kw = {'ambiguous_table_name_map': {}, 'from_linter': None, 'identifier_preparer': , 'type_expression': , ...}

def _compiler_dispatch(
self: Visitable, visitor: Any, **kw: Any
) -> str:
"""Look for an attribute named "visit_" on the
visitor, and call it with the same kw params.

"""
try:
> meth = getter(visitor)
E AttributeError: 'CrateTypeCompiler' object has no attribute 'visit_JSONPATH'

.venv/lib/python3.12/site-packages/sqlalchemy/sql/visitors.py:137: AttributeError
```