【报Bug】在插槽内无法取到插槽参数值，总是为undefined

组件代码如下：

<template>  
    <uni-swiper-dot :info="items" :current="currentAlt" mode="dot">  
        <swiper :current="current" :autoplay="autoplay" indicator-dots indicator-color="#FFFFFF"  
            indicator-active-color="#000000"  
            :style="{height: height + 'px'}"  
            @change="$emit("change", item)">  
            <swiper-item v-for="(item, index) in items" :key="index">  
                <slot :item="item" :index="index" />  
            </swiper-item>  
        </swiper>  
    </uni-swiper-dot>  
</template>  

<script>  
    export default {  
        props: {  
            items: {  
                type: Array,  
                default: []  
            },  
            height: {  
                type: Number,  
                default: 225  
            },  
            autoplay: {  
                type: Boolean,  
                default: false  
            }  
        },  
        data() {  
            return {  
                current: 0,  
                currentAlt: 0  
            }  
        },  
        methods: {  
        }  
    }  
</script>

调用组件代码如下：

<template>  
    <view>  
        <custom-swiper  
            :items="config.swipes" :height="style.swiperHeight" :autoplay="autoplay"  
            #default="{item, index}"  
        >  
            <image :id="'swiper-'+index" :src="item.images[0].url"  
                :mode="showLarge ? 'widthFix' : 'aspectFill'"  
            />  
        </custom-swiper>  
    </view>  
</template>

执行时报错：
[Vue warn]: Property or method "item" is not defined on the instance but referenced during render. Make sure that this property is reactive, either in the data option, or for class-based components, by initializing the property. See: https://vuejs.org/v2/guide/reactivity.html#Declaring-Reactive-Properties.

found in

---> <NavSwiper> at pages/component/navSwiper.vue
pages/index.vue(env: macOS,mp,1.05.2111051; lib: 2.16.1)

调试发现插槽传参时就是undefined：