This DEV-only field was added in 836331ba5f69f2cc53b273ec073fae116db14302 by @sebmarkbage but it's not being used anymore to my knowledge.
}
    } else {
      context = (context: any)._context;
    }
  }
  const newProps = workInProgress.pendingProps;
  const render = newProps.children;
  if (__DEV__) {
    if (typeof render !== 'function') {
      console.error(
        'A context consumer was rendered with multiple children, or a child ' +
          "that isn't a function. A context consumer expects a single child " +
          'that is a function. If you did pass a function, make sure there ' +
          'is no trailing or leading whitespace around it.',
      );
    }
  }
  prepareToReadContext(workInProgress, renderLanes);
  const newValue = readContext(context);
  let newChildren;
  if (__DEV__) {
    ReactCurrentOwner.current = workInProgress;
    setIsRendering(true);
    newChildren = render(newValue);
    setIsRendering(false);
  } else {
    newChildren = render(newValue);
  }
  
  workInProgress.flags |= PerformedWork;