optimizations and cleanup for pull request

supervisor/unit.lua

@@ -725,14 +725,14 @@ function unit.new(reactor_id, num_boilers, num_turbines)
         -- can't be disconnected
         if self.plc_i == nil then return false end
 
+        -- reactor must be stopped and RPS can't be tripped
+        if self.plc_i.get_status().status or self.plc_i.get_db().rps_tripped then return false end
+
         -- alarms must be inactive and not tripping
         for _, alarm in pairs(self.alarms) do
             if not (alarm.state == AISTATE.INACTIVE or alarm.state == AISTATE.RING_BACK) then return false end
         end
 
-        -- reactor must be stopped and RPS can't be tripped
-        if self.plc_i.get_status().status or self.plc_i.get_db().rps_tripped then return false end
-
         return true
     end