syncWithSharedStyle Errors should provide more detail
When running syncWithSharedStyle, if the function attempts to update a sharedStyle that is linked to an external library, it returns an error message. 

<img width="644" alt="Screenshot 2020-04-04 at 23 59 56" src="https://user-images.githubusercontent.com/8508891/78462223-68198700-76d0-11ea-8eaa-cabed2c712be.png">

It would be useful to actually show the details of what that sharedStyle actually was, so that the user could track down the culprit.

I have opened a PR #718 

Hope this helps!