Fix bug in ByteArray.subByteArray implementation for omitted length.

lib/scalarlist/byte_arrays.dart

Index: lib/scalarlist/byte_arrays.dart
diff --git a/lib/scalarlist/byte_arrays.dart b/lib/scalarlist/byte_arrays.dart
index 81e3f2477414af1c778c16cd2ebbb997d00eea95..5a23657f8dbde86c4839a14d059a638879cf2d37 100644
--- a/lib/scalarlist/byte_arrays.dart
+++ b/lib/scalarlist/byte_arrays.dart
@@ -33,8 +33,8 @@ abstract class ByteArray {
    * changes to the returned byte array are visible in this byte array
    * and vice-versa.
    *
-   * Throws [IndexOutOfRangeException] if [start] is negative, or if
-   * `start + length` is greater than the length of this byte array.
+   * Throws [IndexOutOfRangeException] if [start] or [length] are negative, or
+   * if `start + length` is greater than the length of this byte array.
    *
    * Throws [ArgumentError] if [length] is negative.
    */