Nested carousel's next() function returns error #1683

Test case:
https://studio.ensembleui.com/app/9YfZUVl3SC82UZ5Mnf2e/screen/XhljMIbP6DoJfkoxgzjJ

Steps to reproduce:

1. Open above screen, which has a parent carousel, and a child carousel
2. Press Next on step 1 to get to child carousel
3. Press Next on child carousel. This throws error Null check operator used on a null value.