Revert "Don't use async import"

This reverts commit 4d8e3a0.

packages/treemap/src/treemap.tsx

@@ -1,6 +1,5 @@
 import React, { useEffect, useState } from 'react'
 import { useMeasure } from 'react-use'
-import { dividing } from '@kitsuyui/rectangle-dividing'
 
 interface Rect {
   x: number
@@ -114,11 +113,26 @@ export const Treemap = (props: {
   const aspectRatio = props.aspectRatio ?? DEFAULT_ASPECT_RATIO
   const boustrophedon = props.boustrophedon ?? false
   const [inAreas, setInAreas] = useState<Rect[]>([])
+  const [dividing, setDividing] = useState<
+    typeof import('@kitsuyui/rectangle-dividing') | null
+  >(null)
 
   useEffect(() => {
+    ; (async () => {
+      if (dividing) return
+      const d = await import('@kitsuyui/rectangle-dividing')
+      setDividing(d)
+    })()
+  })
+
+  useEffect(() => {
+    if (!dividing) {
+      setInAreas([])
+      return
+    }
     const rect: Rect = { x: 0, y: 0, w: width, h: height }
     const weights = new Float32Array(weightedItems.map(({ weight }) => weight))
-    const ia: Rect[] = dividing(
+    const ia: Rect[] = dividing.dividing(
       rect,
       weights,
       aspectRatio,
@@ -135,6 +149,7 @@ export const Treemap = (props: {
     aspectRatio,
     verticalFirst,
     boustrophedon,
+    dividing,
   ])
 
   const rectInfos = rectsToRectInfos(inAreas)