1.75rem/calc(0.75em + 0.375rem) calc(0.75em + 0.375rem) no-repeat;\n}\n\n.was-validated .custom-select:valid:focus, .custom-select.is-valid:focus {\n  border-color: #28a745;\n  box-shadow: 0 0 0 0.2rem rgba(40, 167, 69, 0.25);\n}\n\n.was-validated .form-check-input:valid ~ .form-check-label, .form-check-input.is-valid ~ .form-check-label {\n  color: #28a745;\n}\n\n.was-validated .form-check-input:valid ~ .valid-feedback,\n.was-validated .form-check-input:valid ~ .valid-tooltip, .form-check-input.is-valid...

0.5rem;\n  margin-top: 0.1rem;\n  font-size: 0.875rem;\n  color: #fff;\n  background-color: var(--bs-success);\n  border-radius: var(--bs-border-radius);\n}\n\n.was-validated :valid ~ .valid-feedback,\n.was-validated :valid ~ .valid-tooltip,\n.is-valid ~ .valid-feedback,\n.is-valid ~ .valid-tooltip {\n  display: block;\n}\n\n.was-validated .form-control:valid, .form-control.is-valid {\n  border-color: var(--bs-form-valid-border-color);\n  padding-right: calc(1.5em + 0.75rem);\n  background-image: u...

- Kubeadm: during join when a check is performed that a Node with the same name already exists in the cluster, make sure the NodeReady condition is properly validated ([#89602](https://github.com/kubernetes/kubernetes/pull/89602), [@kvaps](https://github.com/kvaps)) [SIG Cluster Lifecycle]

app = FastAPI()

@app.get("/items/invalidnone", response_model=Union[Item, None])
def get_invalid_none():
    return None
```

This way the data will be correctly validated, you won't have an internal server error, and the documentation will also reflect that this *path operation* could return `None` (or `null` in JSON).

### Fixes