ParquetTransformer stream doesn't emit error

[annfomenko]

Please add error catcher to _transform method of ParquetTransformer class:

_transform(row, encoding, callback) {
     if (row) {
      this.writer.appendRow(row).then(callback).catch((error) => callback(error));
    } else {
      callback();
    }
}

It allows to listen error on the stream object.

[IvanOfThings]

@annfomenko I think your suggestion also solves the problem of founding a error when applying schema in stream process.

I would make the PR but contributors agreement is not available anymore.

Based on the current code the _transform function should look like this:

  _transform(row, encoding, callback) {
    if (row) {
      this.writer
        .appendRow(row)
        .then((d) => callback(null, d), callback)
        .catch((error) => callback(error));
    } else {
      callback();
    }
  }

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Edited: It is an already open PR to solve that --> #46