The constructor of the itemData object should be upgraded to take a table as input (optional).
The table contains raw item data and the variables should be initialized from it.

E.g. if the constuctor table input is taclled 'itemTable', then the name variable could be initialized with name = itemTable.name.

To make sure that we dont initialize variable we expect to be strings into nil values, some guards should be put on, so it will become.

if itemTable.name then
name = itemTable.name
end

The name variable are earlier initialized as an empty string, so this is only overwrtten if the itemTable got a name value.