Rewrite check for row existence as conditional
Rewrite check for row existence as conditional

Because exceptions can be expensive performance wise (see:
https://docs.python.org/3/faq/design.html#how-fast-are-exceptions).

Since we’re counting the number of rows anyway this doesn’t introduce
any performance overhead there. And I think it’s equally readable/same
number of lines of code.

gov-cjwaszczuk/notifications-admin,gov-cjwaszczuk/notifications-admin,gov-cjwaszczuk/notifications-admin,alphagov/notifications-admin,alphagov/notifications-admin,gov-cjwaszczuk/notifications-admin,alphagov/notifications-admin,alphagov/notifications-admin