Create very-often used methods

functions/common.ts

@@ -0,0 +1,12 @@
+export function jsonError(error: string, status: number) {
+  return jsonResponse(JSON.stringify({ error }), status);
+}
+
+export function jsonResponse(body: string, status = 200) {
+  return new Response(body, {
+    headers: {
+      "content-type": "application/json",
+    },
+    status,
+  });
+}