docs-util: add sidebar link validation in prep script (#12306)

www/packages/build-scripts/src/generate-sidebar.ts

@@ -144,9 +144,7 @@ async function getAutogeneratedTagSidebarItems(
   return items
 }
 
-async function checkItem(
-  item: Sidebar.RawSidebarItem
-): Promise<Sidebar.RawSidebarItem> {
+function validateItem(item: Sidebar.RawSidebarItem): void {
   if (!item.type) {
     throw new Error(
       `ERROR: The following item doesn't have a type: ${JSON.stringify(
@@ -156,9 +154,6 @@ async function checkItem(
       )}`
     )
   }
-  if (item.type === "separator") {
-    return item
-  }
   if (item.type === "sidebar" && !item.sidebar_id) {
     throw new Error(
       `ERROR: The following sidebar item doesn't have a sidebar_id: ${JSON.stringify(
@@ -168,6 +163,25 @@ async function checkItem(
       )}`
     )
   }
+  if (item.type === "link" && !item.path) {
+    throw new Error(
+      `ERROR: The following link item doesn't have a path: ${JSON.stringify(
+        item,
+        undefined,
+        2
+      )}`
+    )
+  }
+}
+
+async function checkItem(
+  item: Sidebar.RawSidebarItem
+): Promise<Sidebar.RawSidebarItem> {
+  if (item.type === "separator") {
+    return item
+  }
+
+  validateItem(item)
 
   if (item.children) {
     item.children = await checkItems(item.children)