Interesting, we do use this same approach. We dont have a column with type Double, so have not come across this error ourselves.
It clearly is the column with Double type and as @sishiramishra says, quite possible that deserialize is trying to cast all values in the column to a double type and even if only one of the row values is null or empty, it fails to cast a null value to a double and therefore fails.
The error wont occur in serialize because it just converts any double to a string, but the other way around is not going to work if there are null values.
Could you inspect the item data (table) at the dispatchers to check what the table values are in the column with Double Type?
May be someone else here has had the same issue. So we have to wait. I am interested in knowning the solution to this issue as well.
Last resort - Workaround
Instead of sending a table with a column double type to the dispatcher (serializing offcourse) try to convert the column which is failing to string instead. That way you know if there are null values, they will be handled gracefully when deserializing and this error wont occur.
Later, in the performer, you can cast the values to double wherever necessary.