diff --git a/src/routes/index.ts b/src/routes/index.ts
index d4dba33..584fa32 100644
--- a/src/routes/index.ts
+++ b/src/routes/index.ts
@@ -6,7 +6,14 @@ export default defineEventHandler(async (event) => {
 
   // parse destination URL
   const destination = getQuery<{ destination?: string }>(event).destination;
-  if (!destination) throw new Error('invalid destination');
+  if (!destination)
+    return sendJson({
+      event,
+      status: 400,
+      data: {
+        error: 'destination query parameter invalid',
+      },
+    });
 
   // proxy
   await proxyRequest(event, destination, {
diff --git a/src/utils/sending.ts b/src/utils/sending.ts
new file mode 100644
index 0000000..2b882f0
--- /dev/null
+++ b/src/utils/sending.ts
@@ -0,0 +1,11 @@
+import { H3Event, EventHandlerRequest } from 'h3';
+
+export function sendJson(ops: {
+  event: H3Event<EventHandlerRequest>;
+  data: Record<string, any>;
+  status?: number;
+}) {
+  setResponseStatus(ops.event, ops.status ?? 200);
+  appendResponseHeader(ops.event, 'content-type', 'application/json');
+  send(ops.event, JSON.stringify(ops.data, null, 2));
+}