Exception on attempt to add new record

[afoeder]

Having managed to get an (empty) record list rendered, clicking the "Add" button above the record list results into the exception message

Exception while rendering TYPO3.Expose:Schema:Acme.Foo.Domain.Model.FooSomething/
newControllerTYPO3.Expose:FormController/
form:
TODO: FormRenderer expects a form definition inside form/

Message comes from \TYPO3\Expose\TypoScript\Objects\FormRenderer::evaluate