Menu - drilldown example showing an error after clicking the toggle

[adamviktora]

After clicking the toggle in this example: https://staging-v6.patternfly.org/components/menus/custom-menus/#with-drilldown, it crashes with this error:

Error: Minified React error # 185; visit https://reactjs.org/docs/error-decoder.html?invariant=185 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.