Not considering some used in the comprehension body when checking the comprehension assignment

[nevumx]

idiomatic/use-some-for-output-vars and style/prefer-some-in-iteration are violated in this playground, even though they shouldn't be: https://play.openpolicyagent.org/p/SQNTZtJ0be

e.g.

build_obj(params) := result if {
	param_paths := {
		"principal": ["principal"],
		"action": ["action"],
		"entity": ["entity"],
	}
	param_objects := [build_object_path(param_paths[param_key], param_value) | some param_key, param_value in params]
	result := object.union_n(param_objects)
}

[anderseknert]

First issue (prefer-some-in-iteration) fixed in #579. On to the next.