Can you help me see why 'line' events are not being emitted?

[brycepj]

Hi, I'm somewhat new to streams, so I assume I'm missing something basic here.

Assuming filePath is defined and associated with a large file, why would end events be emitted, but line events never are? mutatedBuffer isn't really important here, just part of the context. Thanks in advance.

function writeFileLineByLine(filePath) {
  const mutatedBuffer = new MutatedFileBuffer(filePath);

  const lineReader = new LineByLineReader(filePath);

  lineReader.on('line', (line) => {
    // never called
    const mutatedLine = `${line} plus appended`;
    mutatedBuffer.push(mutatedLine);
  });

  lineReader.on('error', (err) => {
    // never called
    console.error(err);
  });

  lineReader.on('end', () => {
    // called
    mutatedBuffer.store();
  });

  return lineReader;
}