Approval activities react differently to script errors than the other activities.

1. Open an approval workflow and make sure it is checked out.
2. On an approval activity, double-click the Approved exit.
3. Add the following script to the Condition field:

   && activity.state != 'faulted'

   This prevents the activity from continuing down the normal path in an error state and ensures that Skipped or Approved is the desired state.

4. Click Update.