Theses are two implmentation of the same components. The component is a label, with two button, one to increase the counter, and one to decrease.
The counter's value can't go bellow zero.
In the first implmentation, there is a tiny bit of logic that is miss placed. This logic is executed when the component is rendered. This is bad because the effect of this logic will never appear.
On the second implementaition the "previous-value" is computed with a corrected value (min 0).