Bug 35204: Prevent an expired password from throwing a 500 error

Bug 35204: Prevent an expired password from throwing a 500 error

Currently when a patron with an expired password is authenticated via the API a 500 error is returned rather than a 400 "Validation failed" error. This patch catches the return value for an expired password and returns the validation failure before the patron search is attempted.

Test plan:
1) Choose a patron and set their password expiry date to a date in the past
2) Send a request to auth/password/validation as an authenticated user with that patron's details
3) The response should be a 500 error
4) Apply patch
5) Repeat steps 1-3 and this time the response should be a 400 code with an error message of  "Password expired"

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>