Update app.py

app.py

@@ -58,7 +58,13 @@ df_main = df_orig.select(
 )
 
 df_main = df_main.with_columns(
-    [pl.col(col).fill_null(0).cast(pl.Int64).alias(col) for col in ["upvotes", "num_comments"]]
+    [
+        pl.when(pl.col(col) == "").then(None).otherwise(pl.col(col))
+        .cast(pl.Int64)
+        .fill_null(0)
+        .alias(col)
+        for col in ["upvotes", "num_comments"]
+    ]
 )
 
 df_main = df_main.rename(