fix: push-manifest.json CSS asset type (#1736)

* fix: CSS in push-manifest was labeled as a script

* docs: Adding changeset

* refactor: Skips over already set file attrs when generating push-manifest

.changeset/shy-poets-sneeze.md

@@ -0,0 +1,5 @@
+---
+'preact-cli': patch
+---
+
+Fix for CSS assets sometimes being mistakenly labeled as 'scripts' in the push-manifest.

packages/cli/lib/lib/webpack/create-load-manifest.js

@@ -41,7 +41,7 @@ module.exports = (assets, namedChunkGroups, isProd) => {
 			const routeJs = assets[`${route}.js`];
 
 			routeManifest[routeJs] = { type: 'script', weight: 0.9 };
-			if (routeCss) routeManifest[routeCss] = { type: 'script', weight: 0.9 };
+			if (routeCss) routeManifest[routeCss] = { type: 'style', weight: 0.9 };
 
 			const path = route.replace(/^route-/, '/').replace(/^\/home/, '/');
 
@@ -52,6 +52,7 @@ module.exports = (assets, namedChunkGroups, isProd) => {
 					asyncFiles.chunks.forEach(asset => {
 						asset.files = asset.files || [];
 						asset.files.forEach(file => {
+							if (routeManifest[file]) return;
 							if (/\.css$/.test(file)) {
 								routeManifest[file] = { type: 'style', weight: 0.9 };
 							} else if (/\.js$/.test(file)) {