Dispatch FSM Segfaults when no items listed for testing in distributed mode

[moralismercatus]

When no element is listed, this transition row in DispatchFSM_ is faulty.

Note the Or_<is_first, ...> meaning that even if !have_next_target, the transition succeeds with subsequent code presuming that have_next_target.

One fix is to add have_next_target thusly: Or_<And_<is_first, have_next_target>, ...>

Not a complete solution because there is no transition representing the case Or_<And_<is_first, Not_<have_next_target>>, ...> which would likely need to transition to an error state.

Or, of course, another fix is to ensure that the presumption that the current transition makes always holds (that if is_first, then have_next_target is always true).