Add StdLib and Rank Table

locale/StdLib/core.lua

@@ -0,0 +1,16 @@
+--- Core module
+-- @module Core
+
+Core = {} --luacheck: allow defined top
+
+--- Errors if the variable evaluates to false, with an optional msg
+-- @param var variable to evaluate
+-- @tparam[opt='missing value'] string msg message
+function Core.fail_if_missing(var, msg)
+    if not var then
+        error(msg or "Missing value", 3)
+    end
+    return false
+end
+
+return Core