Error while running event ModuleInserter::on_gui_click ID 1)
Entity is not valid for blueprint: kr-singularity-beacon

Attempted to export module planner as blueprint string (upper-righthand corner when editing the Module Inserter planner)
Running latest version of Factorio 1.1.101 and latest K2 (v 1.3.23) +SE (v 0.6.120).

The only thing I can suspect is that the planner contains the plans module insert for items which aren't yet researched in game, but this has never been an issue in the past (i.e. it works fine for stuff we don't have yet), but for some reason attempting to export the module inserter planner as string crashes the game.

https://imgur.com/a/0uxInLd

possibly similar crash, running SE/K2 although that shouldn't change anything involved in this crash

module inserter invites the player to copy a selection of machines, which may include belts and other non-machines, and paste it into the module inserter to then apply it to other machines.

when those extras are belts, no crash. when underground pipe, yes crash :(

edit: it's not as simple as this. sometimes crash with belts, maybe sometimes no crash with pipe? i don't know.

the crash occurs when loading the preset, not when creating it

The mod Module Inserter (5.2.4) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event ModuleInserter::on_gui_click (ID 1)
__ModuleInserter__/scripts/gui.lua:434: attempt to index local 'row' (a nil value)
stack traceback:
    __ModuleInserter__/scripts/gui.lua:434: in function 'update_row'
    __ModuleInserter__/scripts/gui.lua:458: in function 'update_contents'
    __ModuleInserter__/scripts/gui.lua:770: in function 'handler'
    __ModuleInserter__/control.lua:697: in function <__ModuleInserter__/control.lua:689>

"Entity is not valid for blueprint: kr-singularity-beacon" seems to be unrelated to naiad's error. But it makes me think if all that hacky way of exporting presets via blueprints is worth the trouble.

related to https://mods.factorio.com/mod/ModuleInserter/discussion/61465d25d331e8482a144097