Describe What This Code Does

QinetiQ runs a telemetry pipeline that pulls live readings off a bank of field sensors. Here is the function a colleague wrote to fetch every sensor's latest reading in parallel.

package telemetry

import "sync"

type Reading struct {
	SensorID string
	Value    float64
}

func ProcessReadings(sensorIDs []string, fetch func(string) (Reading, error)) map[string]float64 {
	results := make(map[string]float64)
	var wg sync.WaitGroup

	for _, id := range sensorIDs {
		wg.Add(1)
		go func() {
			defer wg.Done()
			reading, err := fetch(id)
			if err != nil {
				return
			}
			results[reading.SensorID] = reading.Value
		}()
	}

	wg.Wait()
	return results
}

Walk through what this function does end to end, then say what you would flag about its behavior before letting it run against the real sensor fleet, and why.