revert how viteConfig is detected

index.js

@@ -41,18 +41,18 @@ const resolveSync = (source, resolveOptions, label) => {
 exports.interfaceVersion = 2;
 
 exports.resolve = (source, file, config) => {
-    const { viteConfig } = config;
-    if (!viteConfig) {
-        throw new Error("'viteConfig' option must be a vite config object.");
-    }
-
     log("\nin file:\t", file);
 
     if (resolve.isCore(source)) {
         log("resolved:\t", source);
         return { found: true, path: null };
     }
 
+    const { viteConfig } = config;
+    if (!viteConfig) {
+        throw new Error("'viteConfig' option must be a vite config object.");
+    }
+
     const defaultExtensions = [".mjs", ".js", ".ts", ".jsx", ".tsx", ".json"];
     const { alias, extensions = defaultExtensions } = viteConfig.resolve ?? {};
     const resolveOptions = { basedir: path.dirname(file), extensions };