fix(tab-pane): throws error when using v-if

CHANGELOG.en-US.md

@@ -23,6 +23,7 @@
 - Remove `n-calendar`'s useless `console.log`.
 - Fix loading-bar disappears unexpectl, closes [#343](https://github.com/TuSimple/naive-ui/issues/343).
 - Fix `n-select` doesn't scroll to selected item when menu is opened, closes [#346](https://github.com/TuSimple/naive-ui/issues/346).
+- Fix `n-tab-pane` throws error when using v-if.
 
 ## 2.15.1 (2021-06-30)
 

CHANGELOG.zh-CN.md

@@ -23,6 +23,7 @@
 - 移除 `n-calendar` 无用的 console.log
 - 修复 loading-bar 自动消失，关闭 [#343](https://github.com/TuSimple/naive-ui/issues/343)
 - 修复 `n-select` 打开菜单时没有自动滚动到选中项，关闭 [#346](https://github.com/TuSimple/naive-ui/issues/346)
+- 修复 `n-tab-pane` 在使用 v-if 时报错
 
 ## 2.15.1 (2021-06-30)
 

src/tabs/src/TabPane.tsx

@@ -38,6 +38,7 @@ export const tabPaneProps = {
 export type TabPaneProps = ExtractPublicPropTypes<typeof tabPaneProps>
 
 export default defineComponent({
+  __TAB_PANE__: true,
   name: 'TabPane',
   alias: ['TabPanel'],
   props: tabPaneProps,

src/tabs/src/Tabs.tsx

@@ -378,7 +378,11 @@ export default defineComponent({
       mergedSize,
       $slots: { default: defaultSlot, prefix: prefixSlot, suffix: suffixSlot }
     } = this
-    const children = defaultSlot ? flatten(defaultSlot()) : []
+    const children = defaultSlot
+      ? flatten(defaultSlot()).filter((v) => {
+        return (v.type as any).__TAB_PANE__ === true
+      })
+      : []
     const prefix = prefixSlot ? prefixSlot() : null
     const suffix = suffixSlot ? suffixSlot() : null
     const isCard = type === 'card'