Update app.py

app.py

@@ -337,7 +337,10 @@ async def add_exp(member_id):
                                     # discord_user_id to string
                                     copy_df['discord_user_id'] = copy_df['discord_user_id'].astype(str).str.strip('L')
                                     print("After processing discord_user_id:\n", copy_df['discord_user_id'].head())
-                                
+
+                                    # NaN -> 0
+                                    copy_df['total_exp'] = copy_df['total_exp'].fillna(0)
+
                                     # total_exp to int
                                     copy_df['total_exp'] = copy_df['total_exp'].astype(str).str.strip('L').astype(int)
                                     print("After processing total_exp:\n", copy_df['total_exp'].head())