feat: use -1 instead of 0 for presenting missing evals

src/read_evals.py

@@ -29,7 +29,7 @@ pd.options.mode.copy_on_write = True
 
 def calculate_mean(row):
     if pd.isna(row).any():
-        return 0
+        return -1
     else:
         return row.mean()