Address review comment by making error message even more explicit

Signed-off-by: Emerson Knapp <[email protected]>

rosbag2_compression/include/rosbag2_compression/sequential_compression_writer.hpp

@@ -123,6 +123,10 @@ class ROSBAG2_COMPRESSION_PUBLIC SequentialCompressionWriter
   /**
    * Compress a file and update the metadata file path.
    *
+   * Note: this may log an error without raising an exception in the case that the input file
+   * could not be deleted after compressing. This is an error and should never happen, but given
+   * that the desired output is created, execution will not be halted.
+   *
    * \param compressor An initialized compression context.
    * \param file_relative_to_bag Relative path of the file to compress, as stored in metadata -
    *   meaning the path is relative to the bag base folder.

rosbag2_compression/src/rosbag2_compression/sequential_compression_writer.cpp

@@ -255,7 +255,9 @@ void SequentialCompressionWriter::compress_file(
 
     if (!rcpputils::fs::remove(file_relative_to_pwd)) {
       ROSBAG2_COMPRESSION_LOG_ERROR_STREAM(
-        "Failed to remove uncompressed bag: \"" << file_relative_to_pwd.string() << "\"");
+        "Failed to remove original pre-compressed bag file: \"" <<
+          file_relative_to_pwd.string() << "\". This should never happen - but execution " <<
+          "will not be halted because the compressed output was successfully created.");
     }
   } else {
     ROSBAG2_COMPRESSION_LOG_DEBUG_STREAM(
@@ -270,7 +272,7 @@ void SequentialCompressionWriter::split_bagfile()
   std::lock_guard<std::mutex> compressor_lock(compressor_queue_mutex_);
 
   // Grab last file before calling common splitting logic, which pushes the new filename
-  std::string last_file = metadata_.relative_file_paths.back();
+  const auto last_file = metadata_.relative_file_paths.back();
 
   SequentialWriter::split_bagfile();