Using await for with streams and handling done + onError callbacks - flutter

Question

I am using dart:io's HTTP client to download large files the following way:
final url = Uri.parse(fileUrl);
final request = await httpClient.getUrl(url);
final response = await request.close();
Then I use the response of type HttpClientResponse which implements Stream<List<int>>, where each emitted List<int> represents a chunk of the file being downloaded.
My aim is to "transform" that stream into another one and to do so, I have recently learned of await for + yield which allows to do just that:
Stream<Event> processResponse(HttpClientResponse response) async* {
await for (final List<int> chunk in response) {
yield Event.FileChunk(chunk: chunk);
}
yield const Event.Completed();
}
Initially, and before learning about await for, I intended to use the method Stream<T>.listen which takes 4 parameters:
the onData callback for each emitted value in the stream,
the onError callback to notify errors while emitting values,
the onDone callback to notify the stream is closing and won't be emitting any new values and finally
the cancelOnError boolean parameter that is self-explaining.
By using await for () {}, I believe I cover #1 and #3 since I'll get all emitted values and when done, the code will leave the await for's scope which should mean it's done.
But what about errors? Since these streams will be lengthy and heavy IO streams, surely there can be an IO error at any moment. How are they reported? How can I access their data in order to report those and debug if needed?

Answer 1

Just use good ol' try catch, see this reduced example:
Stream<int> inee()async*{
try{
for (int i = 0; i <= 5; i++) {
if(i==4)throw Exception('Hated number 4');
yield i;
}
}catch(e,st){
print('Catch exception $e');
yield 33;
} finally{
//cleanup of incomplete files
}
}
void main() {
inee().listen(print);
}
The output would be the following:
0
1
2
3
Catch exception Exception: Hated number 4
3
inside the catch you can still yield, log your exceptions . You can also add the logic to delete incomplete files to the finally block.