nav not working center set to true

[rossmc]

Issue description:
When the setting center is set to true, the tns-nav-active does not always correspond correctly to the current slide.

To replicate, go to the center setting demo and click on the next button 3 times, on the 2nd and 3rd clicks the tns-nav-active is the same. Also there are only 4 nav dots for 7 slides.

Demo link/slider setting:
https://ganlanyuan.github.io/tiny-slider/demo/#center_wrapper Center set to true.

Tiny-slider version: 2.9.2 & 2.9.3 Browser name && version: Chrome 92 OS name && version: macOS & Catalina 10.15.7

[pdoreau]

It seems like tns-nav-active is set on visible items. I'd like to highlight a "selected" item. Is there a way to put such a class on a unique item, which is for example the one targeted with goTo ?