1. 
      const nextFiberChild = nextFiber.child;
      const nextFallbackChildSet = nextFiberChild
        ? nextFiberChild.sibling
        : null;
       Not
       bec
      const prevFiberChild = prevFiber.child;
      const prevFallbackChildSet = prevFiberChild
        ? prevFiberChild.sibling
        : null;
      if (
        nextFallbackChildSet != null &&
        prevFallbackChildSet != null &&
        updateFiberRecursively(
          nextFallbackChildSet,
          prevFallbackChildSet,
          nextFiber,
          traceNearestHostComponentUpdate,
        )
      ) {
        shouldResetChildren = true;
      }
    } else if (prevDidTimeout && !nextDidTimeOut) {
       Fal
       1. 
       Not
       2. 
      const nextPrimaryChildSet = nextFiber.child;
      if (nextPrimaryChildSet !== null) {