message: Accept nullable subtable columns in TransactLogParser::parse_one
diff: @@ -2013,8 +2013,8 @@ void TransactLogParser::parse_one(InstructionHandler& handler)
  parser_error();
  StringData name = read_string(m_string_buffer); // Throws
  bool nullable = (Instruction(instr) == instr_InsertNullableColumn);
  - if (REALM_UNLIKELY(nullable && (type == type_Table || type == type_Mixed))) {
  - // Nullability not supported for Table and Mixed columns.
  + if (REALM_UNLIKELY(nullable && (type == type_Mixed))) {
  + // Nullability not supported for Mixed columns.
  parser_error();
  }
  if (!handler.insert_column(col_ndx, DataType(type), name, nullable)) // Throws
  