don't generate numbers on server side

src/app/services/user-input-service.ts

@@ -1,4 +1,5 @@
-import { Injectable, signal } from '@angular/core';
+import { Injectable, signal, PLATFORM_ID, inject } from '@angular/core';
+import { isPlatformBrowser } from '@angular/common';
 import Holidays, { HolidaysTypes } from 'date-holidays';
 import { VacationsNumber } from './calendar-service';
 
@@ -8,15 +9,28 @@ import { VacationsNumber } from './calendar-service';
 	providedIn: 'root'
 })
 export class UserInputService {
+	private platformId = inject(PLATFORM_ID);
+
 	private getRandomNumber(): number {
 		return Math.floor(Math.random() * 9) + 1;
 	}
 
-	vacationNumberSignal = signal<VacationsNumber>({
-		cp: this.getRandomNumber(),
-		rtt: this.getRandomNumber(),
-		other: this.getRandomNumber()
-	});
+	private getInitialValues(): VacationsNumber {
+		if (isPlatformBrowser(this.platformId)) {
+			return {
+				cp: this.getRandomNumber(),
+				rtt: this.getRandomNumber(),
+				other: this.getRandomNumber()
+			};
+		}
+		return {
+			cp: 0,
+			rtt: 0,
+			other: 0
+		};
+	}
+
+	vacationNumberSignal = signal<VacationsNumber>(this.getInitialValues());
 
 	get vacationNumber() {
 		return this.vacationNumberSignal();