message: More detailed error message from BP4 Open()
diff: @@ -395,7 +395,13 @@ void BP4Reader::InitBuffer(const TimePoint &timeoutInstant,
  " was found with an index file but md.0 "
  "has not contained enough data within "
  "the specified timeout of " +
  - std::to_string(timeoutSeconds.count()) + " seconds.");
  + std::to_string(timeoutSeconds.count()) +
  + " seconds. index size = " +
  + std::to_string(metadataIndexFileSize) +
  + " metadata size = " + std::to_string(fileSize) +
  + " expected size = " + std::to_string(expectedMinFileSize) +
  + ". One reason could be if the reader finds old data while "
  + "the writer is creating the new files.");
  }
  }
  }
  