Over-zealous GC in functions returning non-primitives, leading to crashage

(apparent) over-zealous GC in functions returning non-primitives, leading to crashage. A clear example was posted to the list by Robert Poor on April12 2009;\

  fun Element allocateElement() {
          if ((_pool.size() => int size) > 0) {
              _pool[size-1] @=> Element @ element;
              size-1 => _pool.size;
              return element;
          }
          return new Element;
      }