Tracked down a crash at world creation in single player and multiplayer stating that

com.google.gson.JsonParseException: Error loading registry data: Unknown tag: forbidden_arcanus:darkstone_ore_replaceables

The crash is between forbidden_arcanus-1.18.1-2.0.1.jar and biggerreactors-1.18.1-0.6.0-beta.jar

ruled out valhelsia_core-1.18.1-0.3.1.jar (forbidden arcus), quartz-1.18.1-0.0.0-beta.jar (bigger reactors), and phosphophyllite-1.18.1-0.6.0-beta.jar (bigger reactors)

Definitely reproducable by just loading those 5 files

I'm inclined to say that this issue isn't on my side, given that I don't see any of my code or mixins in the stack, along with not touching anything seemingly related.

reported to Bigger Reactors as well BiggerSeries/BiggerReactors#38

and in lieu can use extreme reactors(ExtremeReactors2-1.18.1-2.0.38.jar) which uses zerocore2(ZeroCore2-1.18.1-2.1.11.jar}

Could you please test if it still crashes with f&a 1.18.1-2.0.2?

@stal111 Just tried it myself, crashes still.
Edit: Crashreport https://gist.github.com/Gbergz/41981d60b8e868570ab67ba33a664739

can confirm this bug.
same error as in the log Gbergz sended. same screen, latest mod versions and infinite reproducible;
https://mclo.gs/86yJj0V

Also seeing this issue

Should be fixed in 1.18.1 - 2.0.3. Didn't found the cause but I fixed it for now by simply removing the use of the mentioned tag.