Jumping indexes too far with `next`

Hi there,

I’m experiencing an issue with a slider of 6 items where 4 are visible with perView. It seems that after moving right using next twice, to the last item, the track.details.abs goes to 2 (as it should), but then jumps to 4 for some reason. This causes attempting to move back using prev to go to the index 3, which doesn’t work.

I’m using it in Vue/Nuxt, as so:

<template>
  <section>
    <div ref="carouselWrapper">
      <Card
        v-for="item of items"
        :key="item.name"
        class="keen-slider__slide"
        v-bind="item"
      />
    </div>

    <button @click="slider.prev()">prev</button>

    <button @click="slider.next()">next</button>
  </section>
</template>

<script>
import {
  ref,
  onMounted,
  onBeforeUnmount,
} from '@nuxtjs/composition-api'
import KeenSlider from 'keen-slider'

export default {
  name: 'MyCarousel',
  props: {
    items: {
      type: Array,
      required: true,
    },
  },
  setup(props) {
    const carouselWrapper = ref(null)
    const slider = ref()

    onMounted(() => {
      slider.value = new KeenSlider(carouselWrapper.value, {
        slides: {
          perView: 4,
          spacing: 16,
        },
        created: () => {
          setTimeout(() => {
            // update immediately after mount
            slider.value && slider.value.update()
          }, 0)
        },
      })
    })

    onBeforeUnmount(() => {
      if (slider.value) slider.value.destroy()
    })

    return {
      carouselWrapper,
      slider,
    }
  },
}
</script>

Am I doing something foolish? Or could this be a bug?

[ponciusz]

issue can be easily reproduced by setting high value for spacing.

[rcbyr]

Seems to be fixed by the PR from ponciusz.