fix(schema-org): normalize target to array before merging potentialAction (#709)

The `merge()` function crashed with `TypeError: byType[type].target is not iterable`
during SPA navigation when `potentialAction.target` was an object or string instead
of an array. Normalize to array before spreading.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: harlan-zw

packages/schema-org/src/core/util.ts

@@ -35,8 +35,11 @@ export function merge(target: any, source: any): any {
             const type = action['@type']
             if (byType[type]) {
               // merge target arrays
-              if (action.target && byType[type].target)
-                byType[type].target = [...new Set([...byType[type].target, ...action.target])]
+              if (action.target && byType[type].target) {
+                const a = Array.isArray(byType[type].target) ? byType[type].target : [byType[type].target]
+                const b = Array.isArray(action.target) ? action.target : [action.target]
+                byType[type].target = [...new Set([...a, ...b])]
+              }
             }
             else {
               byType[type] = { ...action }

packages/schema-org/src/nodes/WebSite/index.test.ts

@@ -122,6 +122,25 @@ describe('defineWebSite', () => {
     })
   })
 
+  it('can merge duplicate search actions with object target (#709)', async () => {
+    await useSetup(async (head) => {
+      const schema = defineWebSite({
+        name: 'test',
+        potentialAction: defineSearchAction({
+          target: '/search?query={search_term_string}',
+        }),
+      })
+
+      // simulate SPA navigation re-registering the same schema
+      useSchemaOrg(head, [schema])
+      useSchemaOrg(head, [schema])
+
+      const website = await findNode<WebSite>(head, PrimaryWebSiteId)
+      expect(website?.potentialAction).toBeDefined()
+      expect(website?.potentialAction).toHaveLength(1)
+    })
+  })
+
   it('can handle multiple websites', async () => {
     await useSetup(async (head) => {
       useSchemaOrg(head, [