`sf.apply` not working with dates

[Decezaris]

Using danfo-node, with node 16...

timestamp is a column created from new Date() instance

const sfHourly = df.column('timestamp').apply((date) => {
    const dt = new Date(date);
    dt.setMinutes(0);
    
    return dt;
});

This code throws the following message TypeError: arr.slice is not a function