fix(SW-3442) getLowestRoomPrice - cannot read property of undefined

* fix: getLowestRoomPrice throws when given unexpected data
* dont track lowestRoomPrice if unavailable


Approved-by: Hrishikesh Vaipurkar

packages/booking-flow/lib/contexts/SelectRate/SelectRateContext/calculateNumberOfNights.ts

@@ -0,0 +1,10 @@
+import { dt } from "@scandic-hotels/common/dt"
+
+export function calculateNumberOfNights(
+  fromDate: string | Date | undefined,
+  toDate: string | Date | undefined
+): number {
+  if (!fromDate || !toDate) return 0
+
+  return dt(toDate).diff(dt(fromDate), "day")
+}