fix: Issue with partial range in month-picker mode

Author: Jasenkoo

src/Vue3DatePicker/components/composition/external-internal-mapper.ts

@@ -61,7 +61,9 @@ export const useExternalInternalMapper = (
                 if (isMonthArray(value) && 'month' in value[0] && 'year' in value[0]) {
                     mappedDate = [
                         setDateMonthOrYear(null, +value[0].month, +value[0].year),
-                        setDateMonthOrYear(null, +value[1].month, +value[1].year),
+                        value[1]
+                            ? setDateMonthOrYear(null, +value[1].month, +value[1].year)
+                            : (null as unknown as Date),
                     ];
                 } else if (isMonth(value) && 'month' in value && 'year' in value) {
                     mappedDate = setDateMonthOrYear(null, +value.month, +value.year);

src/Vue3DatePicker/utils/date-utils.ts

@@ -135,7 +135,7 @@ export const getMonthVal = (date: Date): IMonthValue => ({ month: getMonth(date)
 
 export const getMonthValForExternal = (date: Date | Date[]): IMonthValue | IMonthValue[] => {
     if (Array.isArray(date)) {
-        return [getMonthVal(date[0]), getMonthVal(date[1])];
+        return [getMonthVal(date[0]), date[1] ? getMonthVal(date[1]) : (null as unknown as IMonthValue)];
     }
     return getMonthVal(date);
 };