Fix propagation of the user's vite config in vite-based frameworks th…

…at don't use a vite.config.js file

.changeset/clever-elephants-rest.md

@@ -0,0 +1,5 @@
+---
+'@vanilla-extract/vite-plugin': patch
+---
+
+Fixes a bug that prevented propagation of the user's vite config to the `vite-node` compiler in vite-based frameworks that don't use a `vite.config.js` file

packages/vite-plugin/src/index.ts

@@ -119,7 +119,7 @@ export function vanillaExtractPlugin({
     async buildStart() {
       if (mode !== 'transform') {
         const { loadConfigFromFile } = await vitePromise;
-        const configFile = await loadConfigFromFile(
+        const loadedConfigFile = await loadConfigFromFile(
           {
             command: config.command,
             mode: config.mode,
@@ -128,13 +128,18 @@ export function vanillaExtractPlugin({
           config.configFile,
         );
 
+        // Fall back to the resolved config if we couldn't load one. This occurs in frameworks
+        // that use vite but do not use a vite.config.js file.
+        const compilerViteConfig = loadedConfigFile?.config || config;
+
         compiler = createCompiler({
           root: config.root,
           identifiers: getIdentOption(),
           cssImportSpecifier: fileIdToVirtualId,
+          // @ts-expect-error Type of `assetsInclude` do not line up
           viteConfig: {
-            ...configFile?.config,
-            plugins: configFile?.config.plugins?.flat().filter(
+            ...compilerViteConfig,
+            plugins: compilerViteConfig.plugins?.flat().filter(
               (plugin) =>
                 typeof plugin === 'object' &&
                 plugin !== null &&