fix session id selection bug

chat.py

@@ -107,10 +107,9 @@ def refresh_sessions():
         st.session_state[
             "current_sessions"
         ] = st.session_state.session_manager.list_sessions(st.session_state.user_name)
+    
     try:
-        dfl_indx = [
-            x["session_id"] for x in st.session_state.current_sessions
-        ].index("default")
+        dfl_indx = [x["session_id"] for x in st.session_state.current_sessions].index("default" if "" not in st.session_state else st.session_state.sel_session["session_id"])
     except ValueError:
         dfl_indx = 0
     st.session_state.sel_sess = st.session_state.current_sessions[dfl_indx]
@@ -143,7 +142,8 @@ def chat_page():
     st.session_state["session_manager"] = build_session_manager()
     with st.sidebar:
         with st.expander("Session Management"):
-            refresh_sessions()
+            if "current_sessions" not in st.session_state:
+                refresh_sessions()
             st.info("Here you can set up your session! \n\nYou can **change your prompt** here!", 
                     icon="🤖")
             st.info(("**Add columns by clicking the empty row**.\n"
@@ -163,7 +163,7 @@ def chat_page():
             try:
                 dfl_indx = [
                     x["session_id"] for x in st.session_state.current_sessions
-                ].index("default")
+                ].index("default" if "" not in st.session_state else st.session_state.sel_session["session_id"])
             except Exception as e:
                 print("*** ", str(e))
                 dfl_indx = 0