Behaviour of calling Matcher#end after the last match doesn't match java.util.regex

[cushon]

This may be related to #200

public class Repro {
  public static void main(String[] args) {
    {
      System.err.println("re2j");
      var p = com.google.re2j.Pattern.compile("foo");
      var m = p.matcher("foobar");
      while (m.find()) {
        System.err.println(m.start());
      }
      System.err.println(m.end());
    }
    {
      System.err.println("java.util.regex");
      var p = java.util.regex.Pattern.compile("foo");
      var m = p.matcher("foobar");
      while (m.find()) {
        System.err.println(m.start());
      }
      System.err.println(m.end());
    }
  }
}

re2j
0
3
java.util.regex
0
Exception in thread "main" java.lang.IllegalStateException: No match found
	at java.base/java.util.regex.Matcher.checkMatch(Matcher.java:1850)
	at java.base/java.util.regex.Matcher.end(Matcher.java:562)
	at Repro.main(Repro.java:19)