Error while running event beltlayer::on_marked_for_deconstruction (ID 20)
beltlayer/lualib/BaseEditor/BaseEditor.lua:853: attempt to index local 'bpproxy_entity' (a nil value)
stack traceback:
beltlayer/lualib/BaseEditor/BaseEditor.lua:853: in function 'create_deconstruction_proxy'
beltlayer/lualib/BaseEditor/BaseEditor.lua:1118: in function 'on_marked_for_deconstruction'
beltlayer/Editor.lua:367: in function 'on_marked_for_deconstruction'
beltlayer/control.lua:34: in function <beltlayer/control.lua:34>

Error occurred after using the alt-D hotkey to get a deconstruction planner (with a full inventory) and getting a message "could not pick up deconstruction planner etc". I then went into my inventory, found a deconstruction planner there, and marked a belt for deconstruction, which caused a fatal error.

Also, whenever I go to beltlayer it tends to destroy my "item on ground" deconstruction planner. Probably unrelated, but anything is possible.

Still having this error, this time with a normal alt-d deconstruction planner.
Error while running event beltlayer::on_marked_for_deconstruction (ID 20)
beltlayer/lualib/BaseEditor/BaseEditor.lua:853: attempt to index local 'bpproxy_entity' (a nil value)
stack traceback:
beltlayer/lualib/BaseEditor/BaseEditor.lua:853: in function 'create_deconstruction_proxy'
beltlayer/lualib/BaseEditor/BaseEditor.lua:1118: in function 'on_marked_for_deconstruction'
beltlayer/Editor.lua:367: in function 'on_marked_for_deconstruction'
beltlayer/control.lua:34: in function <beltlayer/control.lua:34>

Could you upload the save?

There’s definitely a problem with configured deconstruction planners getting removed accidentally, but it doesn’t explain the crash.

i will as soon as I figure out how, I'm using Space Exploration and a few other mods, but it wasn't repeatedly causing crashes or anything until yesterday.

Are you using Picker Dollies by chance?

No, I hadn't heard of that mod before today. I'm using SE, miniloader, and a bunch of other mods, and added recursive blueprints during this playthrough but the problem happened before and after adding that.
https://www.dropbox.com/s/q4e85ivm8lzqkj6/SE.1.7%20WallOff.zip?dl=0 (I name my save files for the thing I intend to do next after continuing to play

I'm guessing it was a conflict with SE, because SE updated and the problem isn't happening anymore. No action needed I guess