refs https://github.com/TryGhost/Team/issues/2233
**Problem**
When a user clicks an offer link that has an archived tier, the site
blocks and you are no longer able to scroll. This is because the product
for that offer can't be found. This has been fixed by updating the
`isActiveOffer` helper to also check for the existence of the
corresponding tier.
**Solution**
- You no longer are able to create new offers if there are no active
tiers
- A custom message is shown that instructs the user to create a new tier
if there are not active tiers on the offers page
- Improved detection of changes in tiers by correctly reloading the
members utils service after tier changes
- Portal redirects to the homepage for offers with an archived tier
(same behaviour as invalid offers)
- Offers of an archived tier are no longer visible in the dashboard
