typelevel / typelevel/fs2

`Stream.groupWithin` swallowing errors when using `EitherT` effect.

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bug
Dominant language
Scala
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Description

When calling groupWithin on a Stream[EitherT[F, A, *], B] The stream halts on the first left, but completes with a success of the elements up to the left. This behavior is different than the case with IO.raiseError: In this case the stream completes as a failure as expected.

Scastie showing minimal example: https://scastie.scala-lang.org/9jBkYj3QSZqKFvN5uPSVtw

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Research direction

Start with the linked Scastie minimal example and trace Stream.groupWithin with an EitherT effect, comparing it with IO.raiseError. Done means the left is propagated as a failed stream rather than returning the preceding elements as a successful completion, with regression coverage for both cases.

Written by the indexing model from the issue text.

Assessment

Tech stack
scala
Domain
stream-processing
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

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