message: Improve error output of testing DSL
diff: @@ -267,7 +267,9 @@ private:
  elementwise_compare_inspector<U> inspector{x};
  auto xs = this->template peek<typename T::outer_type>();
  auto& x0 = get<0>(xs);
  - CAF_REQUIRE(is<T>(x0));
  + if (!is<T>(x0)) {
  + CAF_FAIL("is<T>(x0) !! " << caf::deep_to_string(x0));
  + }
  CAF_CHECK(inspect(inspector, const_cast<T&>(get<T>(x0))));
  }
  