fix: error json

src/controllers/backup-controller.ts

@@ -150,8 +150,8 @@ export class BackupController extends Controller {
         }),
       },
     ).then(async (r) => {
-      const data = await r.json();
-      if (typeof data === "object" && "error" in data) {
+      const data = await r.text();
+      if (data.includes("error")) {
         console.error(data);
         throw new Error("Backup Error");
       }