So obviously this is a stupid thing to do, but Blender lets you do it and then crashes. It should block the operation with an error message instead.

Broken in git latest.

Repro steps:

1. Create a collection
2. Create an instance of that collection
3. Drag the instance into the collection in the Outliner.

Repeating call stack fragment:

blender.exe!DEG::DepsgraphNodeBuilder::build_collection(LayerCollection * from_layer_collection, Collection * collection) Line 499	C++
blender.exe!DEG::DepsgraphNodeBuilder::build_object_instance_collection(Object * object, bool is_object_visible) Line 706	C++