TypeInfoFactory factory = (options, mapping, _) => mapping.CreateInfo(options, null);

var map = new TypeInfoMappingCollection();
map.AddStructType<decimal>("numeric", factory);
map.AddStructArrayType<decimal>("numeric");

var brokenMap = new TypeInfoMappingCollection();
brokenMap.AddStructType<decimal>("decimal", factory);
brokenMap.AddStructArrayType<decimal>("decimal"); // Mapping not found.