message: add blob instead of string so we don't trigger the assert
diff: @@ -1268,7 +1268,7 @@ public:
  // If the value did not yet exist in the dictionary we add it to the StringHeap
  auto found = !value.IsInlined() && state.dictionary.find(value) == state.dictionary.end()
  ? state.dictionary.insert(string_map_t<uint32_t>::value_type(
  - state.dictionary_heap.AddString(value), new_value_index))
  + state.dictionary_heap.AddBlob(value), new_value_index))
  : state.dictionary.insert(string_map_t<uint32_t>::value_type(value, new_value_index));
  state.estimated_plain_size += value.GetSize() + STRING_LENGTH_SIZE;
  if (found.second) {
  