remove unused error message

Author: butterunderflow

src/res_core.ml

@@ -81,15 +81,6 @@ module ErrorMessages = struct
      ...b}` wouldn't make sense, as `b` would override every field of `a` \
      anyway."
 
-  let _listExprSpread =
-    "Lists can only have one `...` spread, and at the end.\n\
-     Explanation: lists are singly-linked list, where a node contains a value \
-     and points to the next node. `list{a, ...bc}` efficiently creates a new \
-     item and links `bc` as its next nodes. `list{...bc, a}` would be \
-     expensive, as it'd need to traverse `bc` and prepend each item to `a` one \
-     by one. We therefore disallow such syntax sugar.\n\
-     Solution: directly use `concat`."
-
   let variantIdent =
     "A polymorphic variant (e.g. #id) must start with an alphabetical letter \
      or be a number (e.g. #742)"