「sweets」の使い方

I was in Akabane earlier this week. On the way to where I was going, I passed Itoyokado. They had this sign in the window.

Many people make mistakes when talking about dessert. Specifically, the word "sweets" throws people off.

• throw off 【句動】（人）をうろたえさせる (definition from Eijiro on the Web)

The problem is the "s" at the end of the word.

× I had a sweets. <- if you use "a", you have to use a singular noun, but "sweets" is plural
○ I had something sweet.
○ I had a pastry/candy/etc.

Now, there's nothing wrong with how Itoyakado used "sweets", but I suspect that is an accident. The sign reads:

× sweets, gift
○ sweets, gifts

Since they used "gift" as a singular noun, I guess they thought of "sweets" as a singular noun, too. Another possibility is that they meant "dessert gifts".

However, "sweets" has an "s", so it's plural. I seldom hear it used in the singular: "a sweet". Usually we say what kind: a candy, a pastry, a cake, a cookie, or something like that.

Anyway, you had better hurry up if you are planning on buying a gift; it appears Itoyokado only has one left. If other stores are like this, this isn't going to be a very successful holiday season.