https://i.imgur.com/Q7HAjue.png

Please include the steps used to get to this point. Thanks

I think the same message, but here it is as text rather an image which you can't copy and paste from...
steps below as well

16545.109 Script @stdlib/stdlib/core.lua:46: PickerBlueprinter:Index out of inventory bounds.
stack traceback:
stdlib/stdlib/entity/inventory.lua:95: in function 'get_blueprint'
PickerBlueprinter/scripts/bpmirror.lua:33: in function <PickerBlueprinter/scripts/bpmirror.lua:31>
[C]: in function 'pcall'
stdlib/stdlib/event/event.lua:355: in function 'dispatch_event'
stdlib/stdlib/event/event.lua:438: in function <stdlib/stdlib/event/event.lua:389>

This happens any time I try to create a blue print book is all.
It sometimes crashes the game and other times doesn't.

I have a button in the short cut part to create a book, and clicking that causes this every time.

Sorry for not replying. There were no steps. It happened immediately upon clicking the "new blueprint book" icon in the UI.

Same thing here. I notice it's been a few weeks since this was first reported so thought I'd throw in another log file:

407.372 Script @stdlib/stdlib/core.lua:46: PickerBlueprinter:Index out of inventory bounds.
stack traceback:
stdlib/stdlib/entity/inventory.lua:95: in function 'get_blueprint'
PickerBlueprinter/scripts/bpmirror.lua:33: in function <PickerBlueprinter/scripts/bpmirror.lua:31>
[C]: in function 'pcall'
stdlib/stdlib/event/event.lua:355: in function 'dispatch_event'
stdlib/stdlib/event/event.lua:438: in function <stdlib/stdlib/event/event.lua:389>

The only steps needed to reproduce this is to click on the "blueprint book" icon in the shortcut bar.

I thought this got fixed already in a newer version
but I haven't tried it in awhile so I might be thinking of another mod

sometimes it just reported the error but didn't crash the game
other times it did both :(

Fixed in the latest release of stdlib, Thank you

Thank you Nexela, I'll check it out!

Edit: Yup, fixed. You're the best. Thanks for all the work you continue to do for this amazing game!