Stream coordinator: only return tail info if osiris app is started

This ensures that only nodes that are ready to host stream members
are included in the election. This avoids continuous restart attempts
when the rabbit application is stopped.

Author: kjnilsson

deps/rabbit/src/rabbit_stream_coordinator.erl

@@ -782,6 +782,8 @@ get_replica_tail(Node, Conf) ->
     case rpc:call(Node, ?MODULE, log_overview, [Conf]) of
         {badrpc, nodedown} ->
             {error, nodedown};
+        {error, _} = Err ->
+            Err;
         {_Range, Offsets} ->
             {ok, select_highest_offset(Offsets)}
     end.
@@ -792,8 +794,13 @@ select_highest_offset(Offsets) ->
     lists:last(Offsets).
 
 log_overview(Config) ->
-    Dir = osiris_log:directory(Config),
-    osiris_log:overview(Dir).
+    case whereis(osiris_sup) of
+        undefined ->
+            {error, app_not_running};
+        _ ->
+            Dir = osiris_log:directory(Config),
+            osiris_log:overview(Dir)
+    end.
 
 
 replay(L) when is_list(L) ->