ev3go/ev3dev: motorutil/steer.go; 22 LoC

Found a possible issue in [ev3go/ev3dev](https://www.github.com/ev3go/ev3dev) at [motorutil/steer.go](https://github.com/ev3go/ev3dev/blob/8dac9dc96a47a31345255ef1ab871db47016ef7c/motorutil/steer.go#L296-L317)

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 motor used in defer or goroutine at line 311

[Click here to see the code in its original context.](https://github.com/ev3go/ev3dev/blob/8dac9dc96a47a31345255ef1ab871db47016ef7c/motorutil/steer.go#L296-L317)

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

```go
for i, motor := range []struct {
side string
device *ev3dev.TachoMotor
}{
{side: "left", device: s.Left},
{side: "right", device: s.Right},
} {
i := i
side := motor.side
device := motor.device
wg.Add(1)
go func() {
defer wg.Done()
stat, ok, err := ev3dev.Wait(device, ev3dev.Running, 0, 0, false, s.Timeout)
if err != nil {
errors[i] = waitError{side: side, motor: device, cause: err}
}
if !ok {
errors[i] = waitError{side: side, motor: device, cause: timeoutError(s.Timeout), stat: stat}
}
}()
}

```

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See the descriptions of the classifications [here](https://github.com/github-vet/rangeclosure-findings#how-can-i-help) for more information.

commit ID: 8dac9dc96a47a31345255ef1ab871db47016ef7c