Refactor contest file upload logic in app.py for improved session state management

- Removed unnecessary session state clearing to prevent data loss during contest file uploads.
- Enhanced the logic to check for existing contest files before allowing new uploads, ensuring a smoother user experience.
- Maintained existing functionality for loading contest data while improving clarity and efficiency in the upload process.

app.py

@@ -72,21 +72,20 @@ with tab1:
         st.info("Go ahead and upload a Contest file here. Only include player columns and an optional 'Stack' column if you are playing MLB.")
         if parse_type == 'DB Search':
             contest_name_var = st.selectbox("Select Contest to load", name_parse)
-            st.session_state.clear()
             if 'Contest_file' not in st.session_state:
                 if st.button('Load Contest Data', key='load_contest_data'):
                     st.session_state['Contest_file'] = grab_contest_data(sport_select, contest_name_var, contest_id_map, date_select)
             else:
                 pass
         elif parse_type == 'Manual':
-            st.session_state.clear()
-            st.session_state['Contest_upload'] = st.file_uploader("Upload Contest File (CSV or Excel)", type=['csv', 'xlsx', 'xls'])
-            if st.session_state['Contest_upload'] is not None:
-                st.session_state['Contest_file'] = pd.read_csv(st.session_state['Contest_upload'])
-            st.session_state['Contest_file_helper'] = grab_contest_data(sport_select, name_parse.iloc[0], contest_id_map, date_select)
-            if 'Contest' in st.session_state:
-                del st.session_state['Contest']
-
+            if 'Contest_file' not in st.session_state:
+                st.session_state['Contest_upload'] = st.file_uploader("Upload Contest File (CSV or Excel)", type=['csv', 'xlsx', 'xls'])
+                if st.session_state['Contest_upload'] is not None:
+                    st.session_state['Contest_file'] = pd.read_csv(st.session_state['Contest_upload'])
+                st.session_state['Contest_file_helper'] = grab_contest_data(sport_select, name_parse.iloc[0], contest_id_map, date_select)
+            else:
+                pass
+            
         if 'Contest_file' in st.session_state:
             if 'Contest_file_helper' in st.session_state:
                 st.session_state['Contest'], st.session_state['ownership_df'], st.session_state['actual_df'], st.session_state['salary_df'], st.session_state['team_df'], st.session_state['pos_df'], st.session_state['entry_list'], check_lineups = load_contest_file(st.session_state['Contest_file'], st.session_state['Contest_file_helper'], sport_select)