Take a look at the last paragraph (“There is one additional problem…”) in this post here: S4TF in colab (error) - #4 by marcrasi. It should make this error go away, and should also fix similar problems in subsequent notebooks.
Even though that will fix the error, notebookToScript won’t really work like you would expect in Colab. It exports the notebook that is on the disk into a package that can be imported into subsequent notebooks. But when you’re working in Colab, the notebook on disk is not the same as the notebook that you have opened. As long as you’re not trying to import your modifications into subsequent notebooks, this won’t be a problem.