Invalid Avro header does not raise error event about avsc HOT 1 OPEN

Agreed that it's surprising behavior for the stream to not emit an error if it is ended without a valid header. (Until that happens, the tap.isValid return on failed check is expected: it just means the header is missing data.)

Until this is fixed, your workaround sounds right. To contain complexity on your end (and make migration easier later on) you could isolate the logic in a thin factory function. Something like (untested):

function newBlockDecoder(...args) {
  let truncated = true;
  return new avro.streams.BlockDecoder(...args)
    .on('finish', function () { if (truncated) { this.emit('error', new Error('Invalid header')); }})
    .on('metadata', () => { truncated = false; });
}

from avsc.