fix(images): preserve bodyless responses with size headers

src/server/images.ts

@@ -84,6 +84,9 @@ export async function readImageResponseBytes(
     cancelUnlockedResponseBody(response, signal.reason);
     throw signal.reason;
   }
+  if (response.body === null) {
+    return { bytes: new Uint8Array(0), oversized: false };
+  }
 
   const maxBytes = options.maxBytes ?? IMAGES_RESPONSE_MAX_BYTES;
   const contentLength = response.headers.get("content-length");

tests/server-images.test.ts

@@ -783,7 +783,10 @@ test("relays a bodyless upstream image status without synthesizing a body", asyn
   globalThis.fetch = (async (input: RequestInfo | URL, init?: RequestInit) => {
     const requestUrl = typeof input === "string" ? input : input instanceof URL ? input.toString() : input.url;
     if (new URL(requestUrl).hostname === "chatgpt.com") {
-      return new Response(null, { status: 204 });
+      return new Response(null, {
+        status: 204,
+        headers: { "content-length": String(IMAGES_RESPONSE_MAX_BYTES + 1) },
+      });
     }
     return originalFetch(input, init);
   }) as typeof fetch;