handling empty dataframes

app.py

@@ -90,37 +90,53 @@ def init_leaderboard(dataframe):
             interactive=False,
         )
 
+    missing_cols = [col for col in COLS if col not in dataframe.columns]
+    if missing_cols:
+        for col in missing_cols:
+            dataframe[col] = None
+
     column_to_type = {c.name: c.type for c in team_columns}
     datatypes = [column_to_type.get(col, "str") for col in dataframe.columns]
 
     default_selection = [
-        c.name
+        str(c.name)
         for c in team_columns
-        if getattr(c, "displayed_by_default", False) and c.name and c.name in dataframe.columns
+        if getattr(c, "displayed_by_default", False) and c.name is not None and str(c.name) in dataframe.columns
     ]
+
     cant_deselect = [
-        c.name for c in team_columns if getattr(c, "never_hidden", False) and c.name and c.name in dataframe.columns
+        str(c.name)
+        for c in team_columns
+        if getattr(c, "never_hidden", False) and c.name is not None and str(c.name) in dataframe.columns
     ]
+
     hide_cols = [
-        c.name for c in team_columns if getattr(c, "hidden", False) and c.name and c.name in dataframe.columns
+        str(c.name)
+        for c in team_columns
+        if getattr(c, "hidden", False) and c.name is not None and str(c.name) in dataframe.columns
     ]
 
     search_cols = []
     if hasattr(TeamColumn, "team_name") and hasattr(TeamColumn.team_name, "name"):
         search_col_name = TeamColumn.team_name.name
-        if search_col_name and search_col_name in dataframe.columns:
-            search_cols = [search_col_name]
+        if search_col_name is not None and str(search_col_name) in dataframe.columns:
+            search_cols = [str(search_col_name)]
+
+    default_selection = [c for c in default_selection if c is not None]
+    cant_deselect = [c for c in cant_deselect if c is not None]
+    hide_cols = [c for c in hide_cols if c is not None]
+    search_cols = [c for c in search_cols if c is not None]
 
     return Leaderboard(
         value=dataframe,
         datatype=datatypes,
         select_columns=SelectColumns(
-            default_selection=default_selection,
-            cant_deselect=cant_deselect,
+            default_selection=default_selection if default_selection else [],
+            cant_deselect=cant_deselect if cant_deselect else [],
             label="Select Columns to Display:",
         ),
-        search_columns=search_cols,
-        hide_columns=hide_cols,
+        search_columns=search_cols if search_cols else [],
+        hide_columns=hide_cols if hide_cols else [],
         filter_columns=[],
         interactive=False,
     )