asset: targeted fix for loading the initial url quicker, before debouncing (#4058)

This is a more surgical fix while these other diffs are being hashed
out: https://github.com/tldraw/tldraw/pull/4045 and
https://github.com/tldraw/tldraw/pull/4048

Problem was that we always waited a minimum of 500ms and we really
should have a `leading: true` to our debounce.

### Change type

- [x] `bugfix`
- [ ] `improvement`
- [ ] `feature`
- [ ] `api`
- [ ] `other`

### Release notes

- Assets: fix artificial delay in showing an image.

packages/tldraw/src/lib/shapes/shared/useAsset.ts

@@ -1,5 +1,5 @@
 import { TLAssetId, TLShapeId, useEditor, useValue } from '@tldraw/editor'
-import { useEffect, useState } from 'react'
+import { useEffect, useRef, useState } from 'react'
 
 /** @internal */
 export function useAsset(shapeId: TLShapeId, assetId: TLAssetId | null, width: number) {
@@ -8,6 +8,11 @@ export function useAsset(shapeId: TLShapeId, assetId: TLAssetId | null, width: n
 	const asset = assetId ? editor.getAsset(assetId) : null
 	const culledShapes = editor.getCulledShapes()
 	const isCulled = culledShapes.has(shapeId)
+	const didAlreadyResolve = useRef(false)
+
+	useEffect(() => {
+		if (url) didAlreadyResolve.current = true
+	}, [url])
 
 	const shapeScale = asset && 'w' in asset.props ? width / asset.props.w : 1
 	// We debounce the zoom level to reduce the number of times we fetch a new image and,
@@ -21,12 +26,15 @@ export function useAsset(shapeId: TLShapeId, assetId: TLAssetId | null, width: n
 		if (isCulled) return
 
 		let isCancelled = false
-		const timer = editor.timers.setTimeout(async () => {
-			const resolvedUrl = await editor.resolveAssetUrl(assetId, {
-				screenScale,
-			})
-			if (!isCancelled) setUrl(resolvedUrl)
-		}, 500)
+		const timer = editor.timers.setTimeout(
+			async () => {
+				const resolvedUrl = await editor.resolveAssetUrl(assetId, {
+					screenScale,
+				})
+				if (!isCancelled) setUrl(resolvedUrl)
+			},
+			didAlreadyResolve.current ? 500 : 0
+		)
 
 		return () => {
 			clearTimeout(timer)