Fix HTTPError.body forwarding in error handlers

src/runtime/internal/error/dev.ts

@@ -86,6 +86,7 @@ export async function defaultHandler(
         statusText: error.statusText,
         message: error.message,
         data: error.data,
+        ...(error.body || {}),
         stack: error.stack?.split("\n").map((line) => line.trim()),
       }
     : await youch.toHTML(error, {

src/runtime/internal/error/prod.ts

@@ -62,6 +62,7 @@ export function defaultHandler(
     statusText: error.statusText,
     message: isSensitive ? "Server Error" : error.message,
     data: isSensitive ? undefined : error.data,
+    ...(isSensitive ? {} : error.body || {}),
   };
 
   return {

test/fixture/server/routes/api/error-body.ts

@@ -0,0 +1,12 @@
+import { HTTPError } from "nitro/h3";
+
+export default () => {
+  throw new HTTPError({
+    status: 500,
+    message: "Custom error message",
+    data: {
+      instance: "local",
+    },
+    body: { code: "urn:nitro:missing-error-code" },
+  });
+};

test/tests.ts

@@ -422,6 +422,21 @@ export function testNitro(
     expect(data.json.error).toBe(true);
   });
 
+  it("handles errors with body property", async () => {
+    const { status, data } = await callHandler({
+      url: "/api/error-body",
+      headers: {
+        Accept: "application/json",
+      },
+    });
+    expect(status).toBe(500);
+    expect(data.error).toBe(true);
+    expect(data.message).toBe("Custom error message");
+    expect(data.data).toEqual({ instance: "local" });
+    // Body properties should be spread at top level
+    expect(data.code).toBe("urn:nitro:missing-error-code");
+  });
+
   it.skipIf(
     // TODO!
     ctx.preset === "vercel" && ctx.nitro?.options.vercel?.entryFormat === "node" && isWindows