* can propagate through many layers of AbstractTransformFuture up to the root call to set().
     *
     * https://github.com/google/guava/issues/2254
     *
     * Other kinds of Errors are possible:
     *
     * - OutOfMemoryError from allocations in setFuture(): The calculus here is similar to
     * StackOverflowError: We can't reliably call setException(error).
     *