fix jumping into march 01 from january 29

public/js/components/Calendar/Month.js

@@ -26,7 +26,7 @@ export default {
 				this.syncOnNextChange = false;
 				this.focusDate.set(this.date);
 			} else {
-				this.focusDate.m += dir;
+				this.focusDate.moveMonthInDirection(dir)
 			}
 			this.$emit('change:range', {
 				start: new Date(this.focusDate.y, this.focusDate.m, 1), 

public/js/composables/CalendarDate.js

@@ -1,6 +1,11 @@
 import {user_locale} from "../plugin/Phrasen.js";
 import CalendarDates from "./CalendarDates.js";
 
+const monthDayRanges = []
+for(let i = 1; i < 13; i++) {
+	monthDayRanges.push(new Date(1995, i, 0).getDate())
+}
+
 class CalendarDate {
 	constructor(y, m, d) {
 		this.weekStart = CalendarDate.getWeekStart();
@@ -210,6 +215,15 @@ class CalendarDate {
 	cleanup(){
 		if(this.watchLocale && this.watchLocale.stop) this.watchLocale.stop(); // TODO: ?
 	}
+	moveMonthInDirection (dir) {
+		// avoid setting date in wrong month if we try to create a date which does not exist like 30th of february
+		const newM = this.m + dir
+		const maxDaysTarget = monthDayRanges[newM]
+
+		if (this.d > maxDaysTarget) this.d = maxDaysTarget
+		
+		this.m = newM // calls _clean which sets a new Date
+	}
 }
 /**
  * Returns the weekday number (Date.getDay()) on which the week starts depending on the locale.