reopen session if closed (#261)

Co-authored-by: Saimon Michelson <saimon.michelson@gmail.com>

Author: saimonation

cterasdk/clients/async_requests.py

@@ -23,7 +23,7 @@ def __init__(self, settings):
 
     @property
     def session(self):
-        if self._session is None:
+        if self.closed:
             self._session = aiohttp.ClientSession(trace_configs=[async_tracers.default()], **session_parameters(self._settings))
         return self._session