Occurs in Fiber with multiple instances of the React package (which can't share current owner).
return updateCoroutine(returnFiber, oldFiber, newChild, priority);
          } else {
            return null;
          }
        }
        case REACT_YIELD_TYPE: {
          
          
          
          if (key === null) {
            return updateYield(returnFiber, oldFiber, newChild, priority);
          } else {
            return null;
          }
        }
        case REACT_PORTAL_TYPE: {
          if (newChild.key === key) {
            return updatePortal(returnFiber, oldFiber, newChild, priority);
          } else {
            return null;
          }
        }
      }
      if (isArray(newChild) || getIteratorFn(newChild)) {
        
        
        if (key !== null) {
          return null;
        }
        return updateFragment(returnFiber, oldFiber, newChild, priority);