Scheduling: cancelling render from parent can cancel render triggered in child

[sdegueldre]

Playground

Here, onWillUpdateProps is executed and mutates the state, so the component should render, but because there is already a render coming from the parent component, no new render is actually scheduled. When the parent component restores the state to its previous value, the props are no longer different from the commited props and the render from the parent is canceled, and the rendering corresponding to the state mutation is lost in the ether.

in ComponentNode.prototype.render, the lines

if (current) {
  if (!current.bdom && !fibersInError.has(current)) {
    return;
  }
}

make it so that the render coming from the child won't schedule a rendering if one is already scheduled but not completed (ie no bdom), but doesn't account for the fact that this rendering may be canceled by the parent