refactor(VList): make itemType optional in useListItems

fixes #19476

Author: yuwu9145

packages/vuetify/src/components/VList/VList.tsx

@@ -38,7 +38,7 @@ function isPrimitive (value: unknown): value is string | number | boolean {
   return typeof value === 'string' || typeof value === 'number' || typeof value === 'boolean'
 }
 
-function transformItem (props: ItemProps & { itemType: string }, item: any): InternalListItem {
+function transformItem (props: ItemProps & { itemType?: string }, item: any): InternalListItem {
   const type = getPropertyFromItem(item, props.itemType, 'item')
   const title = isPrimitive(item) ? item : getPropertyFromItem(item, props.itemTitle)
   const value = getPropertyFromItem(item, props.itemValue, undefined)
@@ -63,7 +63,7 @@ function transformItem (props: ItemProps & { itemType: string }, item: any): Int
   }
 }
 
-function transformItems (props: ItemProps & { itemType: string }, items: (string | object)[]) {
+function transformItems (props: ItemProps & { itemType?: string }, items: (string | object)[]) {
   const array: InternalListItem[] = []
 
   for (const item of items) {
@@ -73,7 +73,7 @@ function transformItems (props: ItemProps & { itemType: string }, items: (string
   return array
 }
 
-export function useListItems (props: ItemProps & { itemType: string }) {
+export function useListItems (props: ItemProps & { itemType?: string }) {
   const items = computed(() => transformItems(props, props.items))
 
   return { items }

packages/vuetify/src/labs/VTreeview/VTreeview.tsx

@@ -35,7 +35,7 @@ export const makeVTreeviewProps = propsFactory({
     collapseIcon: '$treeviewCollapse',
     expandIcon: '$treeviewExpand',
     slim: true,
-  }), ['nav']),
+  }), ['itemType', 'nav']),
 }, 'VTreeview')
 
 export const VTreeview = genericComponent<new <T>(