While playing around with Debug.locate_references i noticed that it fails on ({}). The problem seems to be that in print_short_svalue_compact the svalue is not completely initialized and at some later point s->subtype is added to a pointer. 1-line patch attached.
Your fix is correct and applied, thanks.
/.../ The current_path variable inherited from the 7.4 compat master is type PIKE_T_FREE for some reason and describe_svalue doesnt like that. /.../
The problem was that low_describe_something had not been teached about the new extern variable concept. Fixed support for getters and setters in it as well.