itchio/wharf: taskgroup/taskgroup.go; 10 LoC

Found a possible issue in [itchio/wharf](https://www.github.com/itchio/wharf) at [taskgroup/taskgroup.go](https://github.com/itchio/wharf/blob/e0beba7413124e6a5a2113df68b98d37f698c7d9/taskgroup/taskgroup.go#L22-L31)

Below is the message reported by the analyzer for this snippet of code. Beware that the analyzer only reports the first issue it finds, so please do not limit your consideration to the contents of the below message.

> range-loop variable i used in defer or goroutine at line 26

[Click here to see the code in its original context.](https://github.com/itchio/wharf/blob/e0beba7413124e6a5a2113df68b98d37f698c7d9/taskgroup/taskgroup.go#L22-L31)

Click here to show the 10 line(s) of Go which triggered the analyzer.

```go
for i, task := range tasks {
go func(task Task) {
err := task()
if err != nil {
done <- errors.WithMessage(err, fmt.Sprintf("task %d", i+1))
return
}
done <- nil
}(task)
}

```

Leave a reaction on this issue to contribute to the project by classifying this instance as a **Bug** :-1:, **Mitigated** :+1:, or **Desirable Behavior** :rocket:
See the descriptions of the classifications [here](https://github.com/github-vet/rangeclosure-findings#how-can-i-help) for more information.

commit ID: e0beba7413124e6a5a2113df68b98d37f698c7d9

Start with taskgroup/taskgroup.go lines 22-31 and the linked analyzer report, then inspect how the goroutine uses the range index. Done means determining whether the finding is a bug, mitigated, or desirable behavior and recording the appropriate reaction.

Written by the indexing model from the issue text.