Golangci lint fixes (#195)

* Add golangci-lin as make target
* Fix: could omit type ... from declaration; it will be inferred from the right-hand side (staticcheck)
* Fix func intArrayContains is unused (unused)
* Fix: could use strings.ReplaceAll instead (staticcheck)
* Fix: could expand call to math.Pow (staticcheck)
* Fix: could use tagged switch on `...` (staticcheck)
* Fix: Error return value of `...` is not checked (errcheck)
* Fix: ineffectual assignment to err (ineffassign)
* Fix: There is no need to wait for command completion
* Add cpustat, diskstat and schedstat config
* Use slices to exclude metrics
* Replaced stringArrayContains by slices.Contains
* Replace m[k]=v loop with maps.Copy
* Use module slices from the standard library. Remove use of golang.org/x/exp/slices
* Use SplitSeq and max to modernize code

collectors/raplMetric.go

@@ -54,9 +54,10 @@ func (m *RAPLCollector) Init(config json.RawMessage) error {
 		return nil
 	}
 
-	var err error = nil
 	m.name = "RAPLCollector"
-	m.setup()
+	if err := m.setup(); err != nil {
+		return fmt.Errorf("%s Init(): setup() call failed: %w", m.name, err)
+	}
 	m.parallel = true
 	m.meta = map[string]string{
 		"source": m.name,
@@ -66,7 +67,7 @@ func (m *RAPLCollector) Init(config json.RawMessage) error {
 
 	// Read in the JSON configuration
 	if len(config) > 0 {
-		err = json.Unmarshal(config, &m.config)
+		err := json.Unmarshal(config, &m.config)
 		if err != nil {
 			cclog.ComponentError(m.name, "Error reading config:", err.Error())
 			return err