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/selfMetric.go

@@ -9,6 +9,7 @@ package collectors
 
 import (
 	"encoding/json"
+	"fmt"
 	"runtime"
 	"syscall"
 	"time"
@@ -34,7 +35,9 @@ type SelfCollector struct {
 func (m *SelfCollector) Init(config json.RawMessage) error {
 	var err error = nil
 	m.name = "SelfCollector"
-	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, "group": "Self"}
 	m.tags = map[string]string{"type": "node"}