Error trapping on discount codes based on Cart contents Is there any automatic Error trapping built into Craft for discount codes for the following rules?  


Orders over a set Total
Orders over a set Quantity


The codes work/apply, but if the rules don’t match I am not getting any errors/messages back.
Any ideas? Do we have to write checks for every scenario?

There are likely more scenarios than the two I have listed above. It seems a little poor UX to appear to do nothing, no error, no discount applied if the contents of the cart don't qualify.
So this is for coupons?

If a coupon can't be applied during an updateCart, you'll get back the rather unhelpful response in JSON of {"error":"Cart not completely updated."}

We intercept this, and because we know it's a coupon operation just replace the text of that to 'Could not apply coupon'.

But it does not give you a reason or anything, unfortunately.