closes https://github.com/TryGhost/Team/issues/3073
Fixed validation error when creating 0% offer. Issue was occurring due
to a falsy check on the offer value. Have resolved by having a more
strict check on the offer value based on the possible empty value it can
be - If creating a new offer without providing an offer value, the value
will be `undefined`. If supplying an offer value, then removing the
offer value, the value will be an empty string. This check prevents `0`
being classed as an invalid value.
closes https://github.com/TryGhost/Team/issues/2380
- improved offer validation for `amount` field to cover all type/amount cases
- added validate-on-blur to the amount field to match our standard validation behaviour
- added re-validation of the amount field when the type is changed and the amount gets reset
- removed the internal parsing of a decimal trial days entry to an integer so the field value matches what is set internally and we let the user know that partial trial days are not supported
Non-user-facing refactors:
- renamed `_saveOfferProperty` to `_updateOfferProperty` to better reflect what it does
- fixed missing indentation for conditional blocks in the offer template
refs https://github.com/TryGhost/Team/issues/1236
Stripe allows coupon names to be only upto 40 chars long, while Ghost allowed them to be 191 chars. This change updates the admin validation to restrict name to 40 chars to match Stripe limit
