It appears that the repository has undergone several changes and renamings:

backend/node_modules/date-fns/locale/sr.js

@@ -1,28 +0,0 @@
-import { formatDistance } from "./sr/_lib/formatDistance.js";
-import { formatLong } from "./sr/_lib/formatLong.js";
-import { formatRelative } from "./sr/_lib/formatRelative.js";
-import { localize } from "./sr/_lib/localize.js";
-import { match } from "./sr/_lib/match.js";
-
-/**
- * @category Locales
- * @summary Serbian cyrillic locale.
- * @language Serbian
- * @iso-639-2 srp
- * @author Igor Radivojević [@rogyvoje](https://github.com/rogyvoje)
- */
-export const sr = {
-  code: "sr",
-  formatDistance: formatDistance,
-  formatLong: formatLong,
-  formatRelative: formatRelative,
-  localize: localize,
-  match: match,
-  options: {
-    weekStartsOn: 1 /* Monday */,
-    firstWeekContainsDate: 1,
-  },
-};
-
-// Fallback for modularized imports:
-export default sr;