'last easter' gives NPE since 2021

[d2a-raudenaerde]

    final List<DateGroup> groups = new Parser().parse("last easter", new Date(121, 1, 1));

java.lang.NullPointerException
	at java.base/java.util.Date.getMillisOf(Date.java:956)
	at java.base/java.util.Date.after(Date.java:929)
	at com.joestelmach.natty.WalkerState.seekToIcsEvent(WalkerState.java:571)
	at com.joestelmach.natty.WalkerState.seekToHoliday(WalkerState.java:393)
	at com.joestelmach.natty.generated.DateWalker.seek(DateWalker.java:1376)
	at com.joestelmach.natty.generated.DateWalker.relative_date(DateWalker.java:713)
	at com.joestelmach.natty.generated.DateWalker.date(DateWalker.java:659)
	at com.joestelmach.natty.generated.DateWalker.date_time(DateWalker.java:585)
	at com.joestelmach.natty.generated.DateWalker.date_time_alternative(DateWalker.java:532)
	at com.joestelmach.natty.generated.DateWalker.parse(DateWalker.java:418)
	at com.joestelmach.natty.Parser.singleParse(Parser.java:220)
	at com.joestelmach.natty.Parser.parse(Parser.java:100)

[d2a-raudenaerde]

    final List<DateGroup> groups = new Parser().parse("last easter", new Date(121, 1, 1));

[mccartney]

It's because the hard-coded festival dates are up to ~2020:
https://github.com/joestelmach/natty/blob/master/src/main/resources/holidays.ics

[arobles-BB]

USA up to 2030