OrdinaryCreateFromConstructor’s signature description indicates that its first argument is a constructor:

The abstract operation OrdinaryCreateFromConstructor takes arguments constructor (a constructor) and intrinsicDefaultProto (a String) and optional argument internalSlotsList [...]

However when this is called from EvaluateGeneratorBody and EvaluateAsyncGeneratorBody, the function that’s passed as the first argument is never a constructor.

The correct type for the first argument is function object. Note that the similarly-misleadingly-named GetPrototypeFromConstructor AO that it delegates to already states the correct type.