Fix ColumnNotFoundError

✅ Solution

The "ColumnNotFoundError" in polars arises when your code references a column name that doesn't exist in the DataFrame, often due to typos, incorrect casing, or failing to create the column before referencing it. Double-check all column names for accuracy and case-sensitivity; ensure the column exists by inspecting the DataFrame's schema or creating it with `pl.lit()` before use if necessary. If you use lazy evaluation, call `collect()` to materialize new columns before accessing them.