When I copied a blueprint into Blueprint Sandboxes, I got a weird error, and it crashed the game.

It is repeatable.

The mod Unfunny Science (0.1.3) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event un-science::on_built_entity (ID 6)
un-science/scripts/atmosphere.lua:15: attempt to index local 'astronomical_object' (a nil value)
stack traceback:
un-science/scripts/atmosphere.lua:15: in function 'on_built'
un-science/control.lua:119: in function <un-science/control.lua:113>

This issue has been fixed . I have reported it earlier in another discussion.

Version: 0.1.05
Bugfixes:
- If no astronomical object is detected for a surface atmospheric collectors do not set a recipe

This shuold apply also to your case.