fix: prevent crash when css is null in Svelte 5

fixes #216

Author: dummdidumm

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## 7.2.0
 
 - Support compiling `svelte.js/ts` files in Svelte 5
+- Prevent crash when `css` is `null` in Svelte 5 ([#216](https://github.com/sveltejs/rollup-plugin-svelte/issues/216))
 
 ## 7.1.6
 

index.js

@@ -169,7 +169,7 @@ module.exports = function (options = {}) {
 				else this.warn(warning);
 			});
 
-			if (emitCss && compiled.css.code) {
+			if (emitCss && compiled.css && compiled.css.code) {
 				const fname = id.replace(new RegExp(`\\${extension}$`), '.css');
 				compiled.js.code += `\nimport ${JSON.stringify(fname)};\n`;
 				cache_emit.set(fname, compiled.css);