It is perhaps unwise to include operator in a path, but BYOND accepts it.

/datum/operator

/datum/operator/proc/test()

This emits a warning that the proc is relatively-pathed, and confuses the language server into thinking the proc is global. If you leave out the first line, it also emits a "bad parent type" error.

/datum/test/proc/test(datum/operator/thing)

This causes a fatal error in the parser.

It would not be unreasonable to just treat operator as a reserved word and disallow its use in paths. OpenDream does this by default. It shouldn't break the parser, though.