Hey,
I ran into an error multiple times the last days.

'''
‘The mod Recursive Blueprints (1.2.3) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event recursive-blueprints::on_tick (ID 0)
invalid key to 'next'
stack traceback:
[C]: in function 'next'
recursive_blueprints/control.lua:89 in function
<recursive-blueprints/control.lua:86>
'''

I am not sure how to reproduce it, however it did happen in the scenario editor. I can provide a corrupted save file if need be.

Changing line 89 in control.lua to
'''
if global.deployers[global.deployer_index] ~= nil then
global.deployer_index = next(global.deployers, global.deployer_index)
else
global.deployer_index = next(global.deployers)
end
'''
allowed me to open the corrupted map again.

Best regards!

Thanks for the report.

A link to the corrupted save would be helpful.

I don't see how this could possibly error just from looking at the lua code.

This is the corrupted save.
https://www.dropbox.com/s/modqs2or3xhh92u/SpiderSEF001_fail.zip?dl=0

To reproduce, open it in the map editor, go to time settings and hit either play or next frame.

Fixed in version 1.2.4.

Thank you :)