chances/party-server: models/playlist.go; 15 LoC

Found a possible issue in [chances/party-server](https://www.github.com/chances/party-server) at [models/playlist.go](https://github.com/chances/party-server/blob/93edf929d741f2e7c40a7f9f56bd8478eb01aac9/models/playlist.go#L123-L137)

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.

> reference to track was used in a composite literal at line 133

[Click here to see the code in its original context.](https://github.com/chances/party-server/blob/93edf929d741f2e7c40a7f9f56bd8478eb01aac9/models/playlist.go#L123-L137)

Click here to show the 15 line(s) of Go which triggered the analyzer.

```go
for _, track := range tracks {
artist := track.FirstArtist()
_, exists := artists[artist]
if exists {
artists[artist] = append(artists[artist], &track)
length := len(artists[artist])
if length > longestLength {
longestLength = length
}
}
artists[artist] = []*Track{&track}
if longestLength == 0 {
longestLength++
}
}

```

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: 93edf929d741f2e7c40a7f9f56bd8478eb01aac9

Open models/playlist.go at lines 123-137 and compare the reported range-loop pointer use with the surrounding context. Decide whether the analyzer finding is a bug, mitigated, or desirable behavior, then record the corresponding reaction; completion is the classification reaction.

Written by the indexing model from the issue text.