`generate_report()` sometimes gives `TypeError: sequence item 0: expected str instance, list found`

Describe the bug
For some, but not all, reports, I'm seeing this error:

    def __violation_report(self, violation: dict, template: Template) -> str:
        nodes_str = ""
        for num, node in enumerate(violation["nodes"], start=1):
>           targets = ", ".join(node["target"])
                      ^^^^^^^^^^^^^^^^^^^^^^^^^
E           TypeError: sequence item 0: expected str instance, list found

To Reproduce

Steps to reproduce the behavior:

1. check out: https://github.com/pycascades/pycascades-2026/tree/39a2096a0edda50c3161cba6b5be232e87b462a6
2. uv run --with-requirements tests/requirements.txt pytest tests

Expected behavior
When findings are found, the assert here should print the findings

Logs
As a workaround, I dumped the results here:
results.txt

Additional context
Add any other context about the problem here.

Start with tests/test_axe.py at the assert around line 104 and reproduce the failure using uv run --with-requirements tests/requirements.txt pytest tests. Trace generate_report() into __violation_report, where joining node["target"] raises the TypeError. Done means findings print as expected and the test suite passes for reports containing these nodes.