fix: throw a useful error if rendering undefined entry (#12113)

* fix: throw a useful error if rendering undefined entry

* Update .changeset/wise-pumas-fry.md

Co-authored-by: Sarah Rainsberger <sarah@rainsberger.ca>

---------

Co-authored-by: Emanuele Stoppa <my.burning@gmail.com>
Co-authored-by: Sarah Rainsberger <sarah@rainsberger.ca>

.changeset/wise-pumas-fry.md

@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Adds a helpful error when attempting to render an undefined collection entry

packages/astro/src/content/runtime.ts

@@ -436,7 +436,11 @@ function updateImageReferencesInData<T extends Record<string, unknown>>(
 export async function renderEntry(
 	entry: DataEntry | { render: () => Promise<{ Content: AstroComponentFactory }> },
 ) {
-	if (entry && 'render' in entry) {
+	if (!entry) {
+		throw new AstroError(AstroErrorData.RenderUndefinedEntryError);
+	}
+
+	if ('render' in entry) {
 		// This is an old content collection entry, so we use its render method
 		return entry.render();
 	}

packages/astro/src/core/errors/errors-data.ts

@@ -1410,6 +1410,17 @@ export const UnknownContentCollectionError = {
 	title: 'Unknown Content Collection Error.',
 } satisfies ErrorData;
 
+/**
+ * @docs
+ * @description
+ * Astro tried to render a content collection entry that was undefined. This can happen if you try to render an entry that does not exist.
+ */
+export const RenderUndefinedEntryError = {
+	name: 'RenderUndefinedEntryError',
+	title: 'Attempted to render an undefined content collection entry.',
+	hint: 'Check if the entry is undefined before passing it to `render()`',
+} satisfies ErrorData;
+
 /**
  * @docs
  * @description

packages/astro/test/content-layer.test.js

@@ -317,5 +317,12 @@ describe('Content Layer', () => {
 			assert.ok(updated.fileLoader[0].data.temperament.includes('Bouncy'));
 			await fixture.resetAllFiles();
 		});
+
+		it('returns an error if we render an undefined entry', async () => {
+			const res = await fixture.fetch('/missing');
+			const text = await res.text();
+			assert.equal(res.status, 500);
+			assert.ok(text.includes('RenderUndefinedEntryError'));
+		});
 	});
 });

packages/astro/test/fixtures/content-layer/src/pages/missing.astro

@@ -0,0 +1,14 @@
+---
+import { getEntry, render } from "astro:content"
+// Skipping the broken page in production so the build doesn't fail
+if(import.meta.env.PROD) {
+	return new Response(null, { status: 404 })
+}
+
+const entry = await getEntry("spacecraft", "missing")
+
+const { Content } = await render(entry)
+
+---
+
+<Content />