#157 Events with no dates assigned should not show invalid date

<staging:8080>/event/ferne-jacobs-on-her-process-and-techniques

Some events will not have dates assigned. This displays as Invalid Date on the post date-info.

I would like…

• When there is no date assigned, the date-info element should not display on the page.

isn’t this an exhibition?

As a fallback if there’s no date entered, the date display should not show invalid date as an error