Story:
WHEN I request GET /entities/items/{item_id} with a valid item ID
AND a generic server or database error occurs
THEN I get 500 HTTP response
AND it contains a unexpected-error code and a message "Unexpected Error"
AND a HTTP header Content-Language set to en
Tasks:
- catch exceptions in the GetItem use case and return a "failure" GetItemResult (with isSuccessful() == false)
- the RouteHandler will create an error response (set http status, code, message) based on the GetItemResult