I was trying use the make a copy of this function with LTN stuff when this mod crashed the game.

The mod Space Exploration Blueprint Fix (0.0.3) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event se-blueprint-fix::on_player_cursor_stack_changed (ID 30)
LuaItemStack API call when LuaItemStack was invalid for read.
stack traceback:
[C]: in function 'get_blueprint_entities'
se-blueprint-fix/control.lua:19: in function 'updateBlueprint'
se-blueprint-fix/control.lua:145: in function <se-blueprint-fix/control.lua:131>

Can you explain more about what you were doing at the time? Were you editing a blueprint book? Was the book empty, or was there an empty blueprint selected in the book? Or perhaps an upgrade planner or deconstruction planner was also in the book?

I pressed the (make a copy of this) botton in a blue print book. The book was not empty no upgrade planner or deconstruction planner in the book. The book is in the My blueprints tab not the Game blueprints tab.

I found the Factorio bug that was causing the problem and submitted a bug report. I also uploaded a new version with a workaround to avoid the crash. Note that the mod might not do what you expect if the blueprint book doesn't show a green selection square around the blueprint you are using. Just shift-scroll once while holding the blueprint to make the green square reappear.