Diagnosing an Invalid Hook Call Error

The component is calling useState conditionally, and the test runner's stricter mode is the first environment to catch the violation.

Jest disables all hooks by default and requires an explicit babel plugin to re-enable them.

Two separate copies of React are loaded — one bundled with the component and a different one bundled into the test environment — so the component's hook calls reach a dispatcher instance that was never initialized by the copy of React actually rendering it, returning null instead of the expected hook implementation.

The component uses a class-based lifecycle method internally, which is incompatible with any hook usage inside its children.