Calendar Crashes While Opening - NSPersistentStoreCoordinator has no persistent stores or NSInternalInconsistencyException
I had the same issue after updating to Sierra.  Saw in some other forums that it was linked to gmail calendar accounts.  Assuming you have a gmail calendar account linked, try disabling the gmail account from Settings and then opening calendar.  Once open you can re-enable the gmail calendar and it works fine (at least for me it does).

Not a solution to the problem, but a temporary fix to allow you to use calendar until Apple figures this out.