Regexp: don't return error when match fails at EOF

bytes/regexp.go

@@ -69,6 +69,9 @@ func Regexp(pattern string) gigaparsec.Parser[byte, string] {
 			return gigaparsec.Result[byte, string]{}, fmt.Errorf("Regexp: reader error: %w", err)
 		}
 		if idx == nil {
+			if err == io.EOF {
+				return gigaparsec.Fail[byte, string](false, gigaparsec.MessageEnd(input.Pos())), nil
+			}
 			got := make([]byte, r.Count())
 			_, _, err = input.Read(got)
 			if err != nil {