Hi,
Please try selecting some of the pages for the testimonial section and click publish in the customizer panel. This should prevent error from appearing.
Also can you please send us some screenshot with the error so that we can get more idea on the error and fix it?
To fix this issue in customize there is two ways:
1. Disable Testimonial section
2. Add any page in “Select the Page” field
But now there is another problem.
There is not possibility to remove page that was added.
1. Click cross icon to delete page from field
2. Publish button is not activated.
3. Change any another field, e.g. Title
4. Publish button is now activated.
5. Click Publish button
6. After saving all is ok
7. Reload customize page and open Testimonial section again.
8. “Select the Page” field contains previous value.
We will look at this problem and probably fix it in our next version.
Thanks