Fix ordering of setting run to be active

Author: kzscisoft

simvue/run.py

@@ -379,11 +379,11 @@ def _start(self, reconnect: bool = False) -> bool:
             self._error(e.args[0])
             return False
 
+        self._active = True
+
         self._dispatcher.start()
         self._heartbeat_thread.start()
 
-        self._active = True
-
         return True
 
     def _error(self, message: str, join_threads: bool = True) -> None: