Fix dialyzer errors in rabbit application

This commit has three fixes that make the dialyzer tests pass for the
rabbit app:

* 'pick_node_in_cluster/1' is only called by a function which asserts
  that the cluster list is non-empty, so the assertion could never
  fail. I've replaced the assertion with an equivalent pattern match in
  the function head.
* 'get_sys_status/1' will fail in its call to 'sys:get_status/1'
  according to the typespec but not in practice when passed a Ra
  server ID ('ra:server_id()' type). I added no-warn attributes to
  suppress those warnings.
* 'check_cluster_consistency/0' would throw its error but the caller
  could handle and bubble-up the error tuple. I have changed it to
  return the error tuple.

Author: the-mikedavis

deps/rabbit/src/rabbit_khepri.erl

@@ -94,6 +94,11 @@
 
 -compile({no_auto_import, [get/1, get/2, nodes/0]}).
 
+%% `sys:get_status/1''s spec only allows `sys:name()' but can work on any
+%% `erlang:send_destination()' including a `ra:server_id()'.
+-dialyzer({nowarn_function, get_sys_status/1}).
+-dialyzer({no_match, [status/0, cluster_status_from_khepri/0]}).
+
 -define(RA_SYSTEM, coordination).
 -define(RA_CLUSTER_NAME, metadata_store).
 -define(RA_FRIENDLY_NAME, "RabbitMQ metadata store").
@@ -157,8 +162,7 @@ add_member(JoiningNode, [_ | _] = Cluster) ->
             {ok, already_member}
     end.
 
-pick_node_in_cluster(Cluster) when is_list(Cluster) ->
-    ?assertNotEqual([], Cluster),
+pick_node_in_cluster([_ | _] = Cluster) when is_list(Cluster) ->
     ThisNode = node(),
     case lists:member(ThisNode, Cluster) of
         true  -> ThisNode;
@@ -404,6 +408,7 @@ status() ->
          end
      end || N <- Nodes].
 
+
 get_sys_status(Proc) ->
     try lists:nth(5, element(4, sys:get_status(Proc))) of
         Sys -> {ok, Sys}
@@ -540,7 +545,7 @@ check_cluster_consistency() ->
         {error, not_found} ->
             ok;
         {error, _} = E ->
-            throw(E)
+            E
     end.
 
 nodes_excl_me(Nodes) -> Nodes -- [node()].