As of v1.3 the credit is no longer available to be used with smartshop or even currency's shop. (i.e. most/all shops will be broken)
It's the way they process the value of the item (they use the item's name and the item's count as it's value), but since v1.3 credits will show as credits:credits and the count should be 1 since that 1 could have the value of many.
As such in v1.3.1 the credits mod must provide it's own shop which can properly use the credits value or their method of value.
This also means that players will get strange and bewildering issues if they use other shop mods as the shop mod doesn't check/use the credits meta value.
To release v1.3.1:
Add a node for credits:shop
Take a peek at smartshop's shop (smartshop:shop) for how they form their gui formspec and modify it (I'm thinking to compensate for requiring usage of our own shop we will have lots of storage and support for selling 6 to 8 items per node/shop)
Test that the new v1.3.1 credits:shop works and works with non credit items too.
Profit!
I estimate about a weeks worth of work provided I focus on this mod and not a new mod or one of my other mods.
It appears minetest.settings object is currently being lame right now...
I expect it to contain the exact same functions that any metaRef object would (set, get, set_int, get_int, set_float, get_float, set_bool, get_bool etc)
Because the minetest.settings object is not the same I need to:
Change it so we can get/check for existence of particular keys
Convert particular values into their correct type (lossless preferred)