fix: Update serializeDefine implementation from upstream vite (#193)

packages/vite-plugin-web-extension/src/plugins/hmr-rewrite-plugin.ts

@@ -24,17 +24,26 @@ export function hmrRewritePlugin(config: {
       : undefined;
 
   // Coped from node_modules/vite, do a global search for: vite:client-inject
-  function serializeDefine(define: any): string {
+  function serializeDefine(define: Record<string, any>): string {
     let res = `{`;
-    for (const key in define) {
+    const keys = Object.keys(define);
+    for (let i = 0; i < keys.length; i++) {
+      const key = keys[i];
       const val = define[key];
-      res += `${JSON.stringify(key)}: ${
-        typeof val === "string" ? `(${val})` : JSON.stringify(val)
-      }, `;
+      res += `${JSON.stringify(key)}: ${handleDefineValue(val)}`;
+      if (i !== keys.length - 1) {
+        res += `, `;
+      }
     }
     return res + `}`;
   }
 
+  function handleDefineValue(value: any): string {
+    if (typeof value === "undefined") return "undefined";
+    if (typeof value === "string") return value;
+    return JSON.stringify(value);
+  }
+
   return {
     name: HMR_REWRITE_PLUGIN_NAME,