fix: make default "template" value to undefined

public/README.md

@@ -36,7 +36,11 @@ Open editor at first.
 <!-- sandpack:{
   "files": {
     "/src/index.js": {
-      "appendCode": "// 次の行は本編とは無関係のコードなので無視してください\nconst link = document.createElement('link');link.rel='stylesheet';link.href='https://jsprimer.net/use-case/todoapp/final/final/index.css';document.head.append(link);\n",
+      "code": "// This is auto generated by vanilla template",
+      "hidden": true
+    },
+    "/src/index2.js": {
+      "appendCode": "// Hack to load css\nconst link = document.createElement('link');link.rel='stylesheet';link.href='https://jsprimer.net/use-case/todoapp/final/final/index.css';document.head.append(link);\n",
       "path": "example2/src/index.js"
     },
     "/src/App.js": {
@@ -51,7 +55,10 @@ Open editor at first.
       "path": "example2/index.html"
     }
   },
+  "entry": "/src/index2.js",
+  "main": "/src/index2.js",
   "environment": "static",
+  "template": "vanilla",
   "options": {
     "showLineNumbers": true,
     "showInlineErrors": true,

src/sandpack.tsx

@@ -29,7 +29,7 @@ export type SandboxOptions = {
     /**
      * What template we use, if not defined we infer the template from the dependencies or files.
      */
-    template?: string;
+    template?: SandpackPredefinedTemplate;
     options?: Record<string, any>; // Refer SandpackInternalProps
     honkitSettings?: {
         isOpen: boolean; // false by default
@@ -115,7 +115,7 @@ export const attachToElement = (element: HTMLElement | ChildNode, options: Sandb
         };
         const entry = options.entry;
         const sandpackOptions = options.options;
-        const template = (options.template ?? "vanilla") as SandpackPredefinedTemplate;
+        const template = options.template;
         currentRoot.render(
             <Sandpack
                 files={files}