Workflow error on Expense Report: 'One or more recipient emails are not valid.'

If Send Email action is used on Expense Report and 'Employee' is chosen as the Recipient, an error is thrown:

'One or more recipient emails are not valid.'

Solution
Use 'Entity (Employee)' instead of 'Employee' in the Workflow > Send Email > Recipient part.

Description
The Workflow shows all options to select, even those on different record types. 'Entity (Employee)' is correct for Expense Report record.