fix: should return 400 in image optimization when Next passes errorMessage

packages/open-next/src/adapters/image-optimization-adapter.ts

@@ -79,6 +79,15 @@ export async function defaultHandler(
       headers,
       queryString === null ? undefined : queryString,
     );
+    // We return a 400 here if imageParams returns an errorMessage
+    // https://github.com/vercel/next.js/blob/512d8283054407ab92b2583ecce3b253c3be7b85/packages/next/src/server/next-server.ts#L937-L941
+    if ("errorMessage" in imageParams) {
+      return buildFailureResponse(
+        new Error(imageParams.errorMessage),
+        options?.streamCreator,
+        400,
+      );
+    }
     let etag: string | undefined;
     // We don't cache any images, so in order to be able to return 304 responses, we compute an ETag from what is assumed to be static
     if (process.env.OPENNEXT_STATIC_ETAG) {
@@ -124,9 +133,6 @@ function validateImageParams(
     false,
   );
   debug("image params", imageParams);
-  if ("errorMessage" in imageParams) {
-    throw new Error(imageParams.errorMessage);
-  }
   return imageParams;
 }
 
@@ -184,6 +190,7 @@ function buildSuccessResponse(
 function buildFailureResponse(
   e: any,
   streamCreator?: StreamCreator,
+  statusCode = 500,
 ): InternalResult {
   debug(e);
   if (streamCreator) {
@@ -192,22 +199,20 @@ function buildFailureResponse(
       async () => void 0,
       streamCreator,
     );
-    response.writeHead(500, {
+    response.writeHead(statusCode, {
       Vary: "Accept",
       "Cache-Control": "public,max-age=60,immutable",
-      "Content-Type": "application/json",
     });
     response.end(e?.message || e?.toString() || "An error occurred");
   }
   return {
     type: "core",
     isBase64Encoded: false,
-    statusCode: 500,
+    statusCode: statusCode,
     headers: {
       Vary: "Accept",
       // For failed images, allow client to retry after 1 minute.
       "Cache-Control": "public,max-age=60,immutable",
-      "Content-Type": "application/json",
     },
     body: toReadableStream(e?.message || e?.toString() || "An error occurred"),
   };

packages/tests-e2e/tests/appRouter/image-optimization.test.ts

@@ -18,3 +18,12 @@ test("Image Optimization", async ({ page }) => {
   await expect(el).toHaveJSProperty("complete", true);
   await expect(el).not.toHaveJSProperty("naturalWidth", 0);
 });
+
+test("should return 400 when validateParams returns an errorMessage", async ({
+  request,
+}) => {
+  const res = await request.get("/_next/image");
+  expect(res.status()).toBe(400);
+  expect(res.headers()["cache-control"]).toBe("public,max-age=60,immutable");
+  expect(await res.text()).toBe(`"url" parameter is required`);
+});