[SLAY-7461] Invited Employer cannot sign on behalf if no default Employer is assigned (Magic Links)

Description: If there is no Default Employer assigned to a learner when a magic link is shared to an Employer, the Employer will be presented with a blank screen when they click on the link and are unable to see any information or sign the Review.

Workaround/Suggested solution: Allocate a Default Employer to the Learners portfolio. 

To assign a Default Employer to a Learner as a Centre Manager or User Manager, follow the steps below: 

1. Click Users in the navigation menu

2. Click the Learner Episodes tab
3. Search for the learner 
4. Click Account
5. Click the Access Accounts tab
6. Select the Employer from the Default Employer drop down list (If the Employer doesn't appear, click Assign Employers. select the employer, click add then Save)
7. Scroll to the bottom of the page and click Save