Update contest session state handling in app.py to improve data integrity

- Added a condition to delete the 'Contest' entry from session state if it is empty after checking for 'Backtesting_upload', enhancing the robustness of data management.
- This change aims to prevent potential errors related to empty contest data and ensures that only valid contest information is retained in the session state.

app.py

@@ -192,6 +192,11 @@ with tab1:
             st.session_state['portfolio_df']['EntryCount'] = len(st.session_state['portfolio_df'])
             
             st.session_state['portfolio_df'] = st.session_state['portfolio_df'][['BaseName', 'EntryCount'] + original_columns]
+
+            if 'Contest' in st.session_state and st.session_state['Contest'][st.session_state['Contest']['BaseName'] == 'Backtesting_upload'].empty:
+                del st.session_state['Contest']
+            else:
+                pass
         except:
             st.session_state['portfolio_df'] = None
             
@@ -250,7 +255,6 @@ with tab2:
             'own_percent_rank': dict(zip(st.session_state['ownership_df']['Player'], st.session_state['ownership_df']['Own'].rank(pct=True)))
         }
         
-
         working_df = st.session_state['Contest'].copy()
         
         # Pre-compute lookup arrays for vectorized operations