Reduction does not appear to work for failed futures

[Frans-Willem]

The following code works, and prints both "Recover on test called" and "Recover on package called"

  // Make a ready resolved future
  auto test = stlab::make_ready_future(stlab::immediate_executor);
  // Create a future that we'll resolve later.
  auto package = stlab::package<void()>(stlab::immediate_executor, []() {});
  // Chain this to-be-resolved future after test.
  test.then([package]() { return package.second; })
      // Chain something to catch resolves/rejections
      .recover([](stlab::future<void> f) {
        std::cout << "Recover on test called" << std::endl;
      })
      .detach();
  // Also stay informed of the package:
  package.second.recover([](stlab::future<void> f) {
    std::cout << "Recover on package called" << std::endl;
  }).detach();
  // Now resolve the chained future.
  package.first();

However, if we have the inner package fail, it will only print "Recover on package called":

  // Make a ready resolved future
  auto test = stlab::make_ready_future(stlab::immediate_executor);
  // Create a future that we'll resolve later.
  auto package = stlab::package<void()>(stlab::immediate_executor, []() {throw std::runtime_error("Oops");});
  // Chain this to-be-resolved future after test.
  test.then([package]() { return package.second; })
      // Chain something to catch resolves/rejections
      .recover([](stlab::future<void> f) {
        std::cout << "Recover on test called" << std::endl;
      })
      .detach();
  // Also stay informed of the package:
  package.second.recover([](stlab::future<void> f) {
    std::cout << "Recover on package called" << std::endl;
  }).detach();
  // Now resolve the chained future.
  package.first();

I'm running a clone from the master branch that is up to date as of today...

[Frans-Willem]

More debugging shows that this only fails when the type of the package is void. When changing to int, things work fine.

[FelixPetriconi]

Frans-Willem, many thanks for the PR!
Fixed in 1.1.1