message: fix: skip difficulties which lead to find the boundary block
diff: @@ -307,13 +307,14 @@ impl<'a> GetBlockSamplesProcess<'a> {
  difficulty_boundary_block_number = last_block_number - last_n_blocks;
  }
  + if difficulty_boundary_block_number > 0 {
  if let Some(total_difficulty) =
  - sampler.get_block_total_difficulty(difficulty_boundary_block_number)
  + sampler.get_block_total_difficulty(difficulty_boundary_block_number - 1)
  {
  difficulty_boundary = total_difficulty;
  difficulties = difficulties
  .into_iter()
  - .take_while(|d| *d < difficulty_boundary)
  + .take_while(|d| *d <= difficulty_boundary)
  .collect();
  } else {
  let errmsg = format!(
  @@ -322,6 +323,9 @@ impl<'a> GetBlockSamplesProcess<'a> {
  );
  return StatusCode::InternalError.with_context(errmsg);
  };
  + } else {
  + difficulties.clear();
  + }
  let sampled_numbers = match sampler.get_block_numbers_via_difficulties(
  start_block_number,
  difficulty_boundary_block_number,
  