added error handling

src/utils/dateUtils.ts

@@ -6,13 +6,18 @@ import moment from 'moment';
  * @param date2 the second date as a string
  * @returns the absolute value of the year difference.
  */
-export function computeYearsBetweenDates(date1: string, date2: string): number {
+export function computeYearsBetweenDates(date1: string, date2: string): number | Error {
+	try {
 		const momentDate1 = moment(date1);
 		const momentDate2 = moment(date2);
 	
 		const yearDiff = momentDate1.diff(momentDate2,'years');
 
 		return Math.abs(yearDiff);
+
+	} catch (error) {
+		return new Error('unable to calculate amount of years');
+	}
 }
 
 /**
@@ -21,11 +26,15 @@ export function computeYearsBetweenDates(date1: string, date2: string): number {
  * @param date2 the second date as a string
  * @returns the absolute value of the month difference.
  */
-export function computeMonthsBetweenDates(date1: string, date2: string): number{
+export function computeMonthsBetweenDates(date1: string, date2: string): number | Error {
+	try {
 		const momentDate1 = moment(date1);
 		const momentDate2 = moment(date2);
 	
 		const monthDiff = momentDate1.diff(momentDate2, 'months');
 	
 		return Math.abs(monthDiff);
+	} catch (error) {
+		return new Error('unable to calculate amount of months');
+	}
 }
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