I get this error from Laravel:

Attempt to read property "id" on null

Here is the code line where the error is generated:

 $count = $lastNumber->id - $lastColumn->id;

Here is the method with that code inside:

/**
 * Count last column extraction
 */
public function countColumn($column)
{
    $lastNumber = Number::all()->sortByDesc('created_at')->first();
    $lastColumn = Number::all()->where('column', '=', $column)->sortByDesc('created_at')->first();
    $count = $lastNumber->id - $lastColumn->id;
    return $count;
}

This is a method of my NumberController.php.

I don’t understand, what is the problem that generates that error? I had try to dd() the 2 variables $lastNumber and $lastColumn and I see a result so the variable its not empty or null.

What am I doing wrong?