refactor: remove non-null assertions

depends on vuejs/vue#9154

Author: KaelWD

packages/vuetify/src/components/VBadge/VBadge.ts

@@ -59,7 +59,7 @@ export default mixins(
       staticClass: 'v-badge',
       'class': this.classes
     }, [
-      this.$slots.default!,
+      this.$slots.default,
       h('transition', {
         props: {
           name: this.transition,

packages/vuetify/src/components/VBtn/VBtn.ts

@@ -119,25 +119,19 @@ export default baseMixins.extend<options>().extend({
       return this.$createElement(
         'div',
         { 'class': 'v-btn__content' },
-        [this.$slots.default!]
+        this.$slots.default
       )
     },
     genLoader (): VNode {
-      const children: VNodeChildren = []
-
-      if (!this.$slots.loader) {
-        children.push(this.$createElement(VProgressCircular, {
-          props: {
-            indeterminate: true,
-            size: 23,
-            width: 2
-          }
-        }))
-      } else {
-        children.push(this.$slots.loader)
-      }
-
-      return this.$createElement('span', { 'class': 'v-btn__loading' }, children)
+      return this.$createElement('span', {
+        class: 'v-btn__loading'
+      }, this.$slots.loader || [this.$createElement(VProgressCircular, {
+        props: {
+          indeterminate: true,
+          size: 23,
+          width: 2
+        }
+      })])
     },
     onRouteChange () {
       if (!this.to || !this.$refs.link) return
@@ -155,10 +149,12 @@ export default baseMixins.extend<options>().extend({
   render (h): VNode {
     const setColor = (!this.outline && !this.flat && !this.disabled) ? this.setBackgroundColor : this.setTextColor
     const { tag, data } = this.generateRouteLink(this.classes)
-    const children = [this.genContent()]
+    const children = [
+      this.genContent(),
+      this.loading && this.genLoader()
+    ]
 
-    tag === 'button' && (data.attrs!.type = this.type)
-    this.loading && children.push(this.genLoader())
+    if (tag === 'button') data.attrs!.type = this.type
 
     data.attrs!.value = ['string', 'number'].includes(typeof this.value)
       ? this.value

packages/vuetify/src/components/VChip/VChip.ts

@@ -63,13 +63,12 @@ export default mixins(Colorable, Themeable, Toggleable).extend({
       ])
     },
     genContent (h: CreateElement): VNode {
-      const children: VNodeChildren = [this.$slots.default!]
-
-      this.close && children.push(this.genClose(h))
-
       return h('span', {
         staticClass: 'v-chip__content'
-      }, children)
+      }, [
+        this.$slots.default,
+        this.close && this.genClose(h)
+      ])
     }
   },
 

packages/vuetify/src/components/VExpansionPanel/VExpansionPanelContent.ts

@@ -142,11 +142,6 @@ export default mixins<options &
   },
 
   render (h): VNode {
-    const children = []
-
-    this.$slots.header && children.push(this.genHeader())
-    children.push(h(VExpandTransition, [this.genBody()]))
-
     return h('li', {
       staticClass: 'v-expansion-panel__container',
       class: this.containerClasses,
@@ -156,6 +151,9 @@ export default mixins<options &
       on: {
         keydown: this.onKeydown
       }
-    }, children)
+    }, [
+      this.$slots.header && this.genHeader(),
+      h(VExpandTransition, [this.genBody()])
+    ])
   }
 })

packages/vuetify/src/components/VProgressCircular/VProgressCircular.ts

@@ -131,7 +131,7 @@ export default mixins(Colorable).extend({
   },
 
   render (h): VNode {
-    const info = h('div', { staticClass: 'v-progress-circular__info' }, [this.$slots.default!])
+    const info = h('div', { staticClass: 'v-progress-circular__info' }, this.$slots.default)
     const svg = this.genSvg(h)
 
     return h('div', this.setTextColor(this.color, {

packages/vuetify/src/components/VRating/VRating.ts

@@ -16,7 +16,7 @@ import { createRange } from '../../util/helpers'
 import mixins from '../../util/mixins'
 
 // Types
-import { VNode, VNodeDirective, VNodeChildrenArrayContents } from 'vue'
+import { VNode, VNodeDirective, VNodeChildren } from 'vue'
 
 type ItemSlotProps = {
   index: number
@@ -188,7 +188,7 @@ export default mixins(
     onMouseLeave (): void {
       this.runDelay('close', () => (this.hoverIndex = -1))
     },
-    genItem (i: number): VNode | VNodeChildrenArrayContents | string {
+    genItem (i: number): VNode | VNodeChildren | string {
       const props = this.createProps(i)
 
       if (this.$scopedSlots.item) return this.$scopedSlots.item(props)

packages/vuetify/src/components/VSnackbar/VSnackbar.ts

@@ -71,28 +71,22 @@ export default mixins(
   },
 
   render (h): VNode {
-    const children: VNodeChildrenArrayContents = []
-
-    if (this.isActive) {
-      children.push(
-        h('div', {
-          staticClass: 'v-snack',
-          class: this.classes,
-          on: this.$listeners
-        }, [
-          h('div', this.setBackgroundColor(this.color, {
-            staticClass: 'v-snack__wrapper'
-          }), [
-            h('div', {
-              staticClass: 'v-snack__content'
-            }, this.$slots.default)
-          ])
-        ])
-      )
-    }
-
     return h('transition', {
       attrs: { name: 'v-snack-transition' }
-    }, children)
+    }, this.isActive && [
+      h('div', {
+        staticClass: 'v-snack',
+        class: this.classes,
+        on: this.$listeners
+      }, [
+        h('div', this.setBackgroundColor(this.color, {
+          staticClass: 'v-snack__wrapper'
+        }), [
+          h('div', {
+            staticClass: 'v-snack__content'
+          }, this.$slots.default)
+        ])
+      ])
+    ])
   }
 })

packages/vuetify/src/components/VTimeline/VTimelineItem.ts

@@ -57,16 +57,12 @@ export default mixins(
       }, this.icon)
     },
     genInnerDot () {
-      const children = []
-
-      this.hasIcon && children.push(this.genIcon())
-
       const data: VNodeData = this.setBackgroundColor(this.color)
 
       return this.$createElement('div', {
         staticClass: 'v-timeline-item__inner-dot',
         ...data
-      }, children)
+      }, [this.hasIcon && this.genIcon()])
     },
     genDot () {
       return this.$createElement('div', {
@@ -80,7 +76,7 @@ export default mixins(
     genOpposite () {
       return this.$createElement('div', {
         staticClass: 'v-timeline-item__opposite'
-      }, [this.$slots.opposite!])
+      }, this.$slots.opposite)
     }
   },
 

packages/vuetify/src/components/VTreeview/VTreeview.ts

@@ -327,7 +327,7 @@ export default mixins(
     const children: VNodeChildrenArrayContents = this.items.length
       ? this.items.map(VTreeviewNode.options.methods.genChild.bind(this))
       /* istanbul ignore next */
-      : this.$slots.default!
+      : this.$slots.default! // TODO: remove type annotation with TS 3.2
 
     return h('div', {
       staticClass: 'v-treeview',

packages/vuetify/src/components/VTreeview/VTreeviewNode.ts

@@ -162,11 +162,10 @@ export default mixins<options>(
       }, [this.text])
     },
     genContent () {
-      // TODO: remove non-null assertions (vuejs/vue#8498)
       const children = [
-        this.$scopedSlots.prepend! && this.$scopedSlots.prepend!(this.scopedProps),
+        this.$scopedSlots.prepend && this.$scopedSlots.prepend(this.scopedProps),
         this.genLabel(),
-        this.$scopedSlots.append! && this.$scopedSlots.append!(this.scopedProps)
+        this.$scopedSlots.append && this.$scopedSlots.append(this.scopedProps)
       ]
 
       return this.$createElement('div', {