Users by default don't have any rights to view properties from the system.user entity (the Generalization that is most likely used for your Account object).
If you are filtering on any of those fields you need to either be an administrator with the right to manage users from all user roles or specific userroles (found in the project security when editing a user role).
Otherwise, you will not be able to view those values and your xpath will trigger an error. I do agree that this should be a clear error in the runtime log and not just an error in the javascript.
We ended up resolving this error by removing the DataGrid where this was happening, and creating a new one that is exactly the same as the old one.
So it seems like our model was corrupt in this case.