fix(InferSeoMetaPlugin): function title templates not respected

Fixes harlan-zw/nuxt-seo-utils#53

Author: harlan-zw

Diff for: packages/unhead/src/unhead.ts

@@ -153,7 +153,7 @@ export function createUnhead<T = ResolvableHead>(resolvedOptions: CreateHeadOpti
 
       if (titleTemplate) {
         const titleTemplateFn = titleTemplate?.textContent
-        head._titleTemplate = typeof titleTemplateFn === 'string' ? titleTemplateFn : undefined
+        head._titleTemplate = titleTemplateFn
         if (titleTemplateFn) {
           // @ts-expect-error todo
           let newTitle = (typeof titleTemplateFn === 'function' ? titleTemplateFn(title?.textContent) : titleTemplateFn)

Diff for: packages/unhead/test/unit/plugins/infer-seo-meta.test.ts

@@ -268,4 +268,35 @@ describe('inferSeoMetaPlugin', () => {
       }
     `)
   })
+  it('infers og:title from function titleTemplate with default value', async () => {
+    const head = createHead({
+      disableDefaults: true,
+      plugins: [InferSeoMetaPlugin()],
+    })
+
+    // Simulate the app.vue setup with a function titleTemplate
+    head.push({
+      title: null,
+      titleTemplate: (titleChunk) => {
+        return titleChunk ? `${titleChunk} - Website` : 'Welcome to Website'
+      },
+      meta: [
+        {
+          name: 'description',
+          content: 'Description.',
+        },
+        {
+          name: 'theme-color',
+          content: '#007ed4',
+        },
+      ],
+    })
+
+    const result = await renderSSRHead(head)
+
+    expect(result.headTags).toContain('<title>Welcome to Website</title>')
+    expect(result.headTags).toContain('<meta property="og:title" data-infer="" content="Welcome to Website">')
+    expect(result.headTags).toContain('<meta name="description" content="Description.">')
+    expect(result.headTags).toContain('<meta name="theme-color" content="#007ed4">')
+  })
 })