message: Add era ID to error message.
diff: @@ -207,7 +207,7 @@ where
  for era_id in (earliest_era.value()..current_era.value()).map(EraId::from) {
  let switch_block = storage
  .read_switch_block_header_by_era_id(era_id)?
  - .ok_or_else(|| anyhow::Error::msg("No such switch block"))?;
  + .ok_or_else(|| anyhow::Error::msg(format!("No such switch block in {}", era_id)))?;
  switch_blocks.push(switch_block);
  }
  