_2019-09-29_

 *  Fix: Cancel calls that fail due to unexpected exceptions. We had a bug where an enqueued call
    would never call back if it crashed with an unchecked throwable, such as a
    `NullPointerException` or `OutOfMemoryError`. We now call `Callback.onFailure()` with an
    `IOException` that reports the call as canceled. The triggering exception is still delivered to
    the thread's `UncaughtExceptionHandler`.

   *
   * <p><b>Note:</b> The current implementation eagerly allocates storage for {@code size} elements.
   * As a consequence, passing values like {@code Integer.MAX_VALUE} can lead to {@link
   * OutOfMemoryError}.
   *
   * @param iterator the iterator to return a partitioned view of
   * @param size the desired size of each partition (the last may be smaller)