some tweak to prevent crash

config/obsw_com_config.py

@@ -47,8 +47,8 @@ def set_communication_interface(tmtc_printer: TmTcPrinter) -> Union[Communicatio
             communication_interface = DummyComIF(tmtc_printer=tmtc_printer)
         if not communication_interface.valid:
             LOGGER.warning("Invalid communication interface!")
-            return None
-        communication_interface.initialize()
+        else:
+            communication_interface.initialize()
         return communication_interface
     except (IOError, OSError):
         LOGGER.error("Error setting up communication interface")

obsw_tmtc_client.py

@@ -123,16 +123,12 @@ class TmTcHandler:
             com_interface=self.communication_interface, tm_timeout=g.G_TM_TIMEOUT,
             tc_timeout_factor=g.G_TC_SEND_TIMEOUT_FACTOR
         )
-        self.initialize_com_if_and_listener()
-        atexit.register(keyboard_interrupt_handler, com_interface=self.communication_interface)
-
-    def initialize_com_if_and_listener(self):
-        if not self.communication_interface.valid:
+        if self.communication_interface.valid:
+            self.tm_listener.start()
+        else:
             LOGGER.info("No communication interface set for now")
             LOGGER.info("TM listener will not be started")
-            return
-
-        self.tm_listener.start()
+        atexit.register(keyboard_interrupt_handler, com_interface=self.communication_interface)
 
     def perform_operation(self):
         """
@@ -185,6 +181,8 @@ class TmTcHandler:
             service_queue = deque()
             service_queue_packer = ServiceQueuePacker()
             service_queue_packer.pack_service_queue(g.G_SERVICE, service_queue)
+            if not self.communication_interface.valid:
+                return
             LOGGER.info("Performing service command operation")
             sender_and_receiver = SequentialCommandSenderReceiver(
                 com_interface=self.communication_interface, tmtc_printer=self.tmtc_printer,