[No GBP] Actually fix random recipes for real (#95895)

## About The Pull Request
Just the fix parts from #95892
Fixes #95876
## Why It's Good For The Game
## Changelog
🆑
fix: metalgen and secret sauce should now generate properly
/🆑

---------

Co-authored-by: l0 <-->

code/controllers/subsystem/persistence/recipes.dm

@@ -6,6 +6,8 @@
 	//asert globchems done
 	for(var/randomized_type in subtypesof(/datum/chemical_reaction/randomized))
 		var/datum/chemical_reaction/randomized/R = GLOB.chemical_reactions_list[randomized_type]
+		if(!R)
+			continue
 		file_data["[R.type]"] = list(
 			timestamp = R.created,
 			required_reagents = R.required_reagents,