Jira Ticket: https://projects.engineering.redhat.com/browse/CWFHEALTH-460

Initially the scope of this task was to catch an error caused from an invalid subject identifier, thus preventing a status 500 error. As that change has been made after the creation of this ticket the new task is to add in code to catch the specific error that is caused from invalid identifiers. Currently, when an invalid subject identifier is entered the user will receive a response of "unexpected error". To give more transparency to the user for the reason of error we are adding in code to catch the specific exception and returning a friendlier response.