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

backend/node_modules/date-fns/isTomorrow.js

@@ -1,37 +0,0 @@
-import { addDays } from "./addDays.js";
-import { constructNow } from "./constructNow.js";
-import { isSameDay } from "./isSameDay.js";
-
-/**
- * The {@link isTomorrow} function options.
- */
-
-/**
- * @name isTomorrow
- * @category Day Helpers
- * @summary Is the given date tomorrow?
- * @pure false
- *
- * @description
- * Is the given date tomorrow?
- *
- * @param date - The date to check
- * @param options - An object with options
- *
- * @returns The date is tomorrow
- *
- * @example
- * // If today is 6 October 2014, is 7 October 14:00:00 tomorrow?
- * const result = isTomorrow(new Date(2014, 9, 7, 14, 0))
- * //=> true
- */
-export function isTomorrow(date, options) {
-  return isSameDay(
-    date,
-    addDays(constructNow(options?.in || date), 1),
-    options,
-  );
-}
-
-// Fallback for modularized imports:
-export default isTomorrow;