See #17798
W
         w
        throw Error('Unable to find node on an unmounted component.');
      }
      if (a.return !== b.return) {
         T
         f
         b
         s
        a = parentA;
        b = parentB;
      } else {
         T
         d
         w
        
         S
        let didFindChild = false;
        let child = parentA.child;
        while (child) {
          if (child === a) {
            didFindChild = true;
            a = parentA;
            b = parentB;
            break;
          }
          if (child === b) {
            didFindChild = true;
            b = parentA;
            a = parentB;