Hiya! In 53:prototypes/create_stack.lua (function DBL.create_stacked_item), the check for icon_size needing to be defined is no longer necessary for 2.0, as the default icon_size is 64. Fortunately you don't even need to change line 56, since if icon_size is nil on the item, you can still set it and pass the nil along, keeping the default value of 64 intact. Not a big issue, but would be nice to not have to specify icon_size on my items when it's technically redundant.

This would also be especially nice, since the error isn't obvious without looking into the log files, since the crash occurs on line 124 of create_stack.lua, where it tries to get the icons value of the item that failed to generate.