jeromelesaux/facerecognition: model/model.go; 22 LoC

Found a possible issue in [jeromelesaux/facerecognition](https://www.github.com/jeromelesaux/facerecognition) at [model/model.go](https://github.com/jeromelesaux/facerecognition/blob/10512e19f1a4f3b17802d621e0754225f471968f/model/model.go#L240-L261)

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 r used in defer or goroutine at line 247

[Click here to see the code in its original context.](https://github.com/jeromelesaux/facerecognition/blob/10512e19f1a4f3b17802d621e0754225f471968f/model/model.go#L240-L261)

Click here to show the 22 line(s) of Go which triggered the analyzer.

```go
for i, r := range fd.GetFaces() {
wc.Add(1)
go func() {
defer wc.Done()
b := make([]byte, 16)
rand.Read(b)
id := fmt.Sprintf("tofind-%X", b)
dstRect := image.Rect(r.X, r.Y, (r.X + r.Width), (r.Y + r.Height))
dst := image.NewRGBA(dstRect)
draw.Draw(dst, dstRect, fd.Image, image.Point{r.X, r.Y}, draw.Src)
filename := GetConfig().GetTmpDirectory() + "face_" + id + "_" + strconv.Itoa(r.X) + "_" + strconv.Itoa(r.Y) + "_" + strconv.Itoa(r.Width) + "_" + strconv.Itoa(r.Height) + strconv.Itoa(i) + ".png"
fdst, _ := os.Create(filename)
defer fdst.Close()
png.Encode(fdst, dst)
logger.Log("File " + filename + "saved as png.")
newFilename := ToPgm(filename)
os.Remove(filename)
normalizeImage(fl, newFilename)
mats = append(mats, ToMatrix(newFilename).Vectorize())
filesnames = append(filesnames, newFilename)
}()
}

```

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: 10512e19f1a4f3b17802d621e0754225f471968f

Start by reading model/model.go around lines 240-261 and the analyzer warning about the range-loop variable used by the goroutine. Check the surrounding face-processing flow before making a focused change; done means the warning is addressed while the generated face files and matrix results still behave as intended.

Written by the indexing model from the issue text.