A user tried to edit an existing (and working) SP Page Builder page. When she saved her changes, she got this error message:

Object of class stdClass could not be converted to string

Now trying to access the page only results in this error. It is possible to open the page structure editor in the backend under SP Page Builder, but the page itself and the frontend editor only results in this error. Also as a Super Admin I cannot access the page.

How do we recover the page, and how do we prevent this in future?