Noticed a hardcoded hyphen in the standard CategorizeEventsByStreamPath projection. Replaced it with the passed in separator.
replace hardcoded dash with _separator
It is not easy as changing this only place. The _separator in this class tells how to extract category from the stream id. You can configure it as projection arguments.
The $ce- prefix defines an index stream for a category. While I agree it is better to use a constant everywhere, changing it will break consumers of index streams that rely on this naming convention.