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/cpufreqCpuinfoMetric.go

@@ -41,9 +41,10 @@ func (m *CPUFreqCpuInfoCollector) Init(config json.RawMessage) error {
 		return nil
 	}
 
-	m.setup()
-
 	m.name = "CPUFreqCpuInfoCollector"
+	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,
@@ -56,7 +57,6 @@ func (m *CPUFreqCpuInfoCollector) Init(config json.RawMessage) error {
 	if err != nil {
 		return fmt.Errorf("failed to open file '%s': %v", cpuInfoFile, err)
 	}
-	defer file.Close()
 
 	// Collect topology information from file cpuinfo
 	foundFreq := false
@@ -86,6 +86,10 @@ func (m *CPUFreqCpuInfoCollector) Init(config json.RawMessage) error {
 			}
 		}
 
+		if err := file.Close(); err != nil {
+			return fmt.Errorf("%s Init(): Call to file.Close() failed: %w", m.name, err)
+		}
+
 		// were all topology information collected?
 		if foundFreq &&
 			len(processor) > 0 &&
@@ -140,7 +144,13 @@ func (m *CPUFreqCpuInfoCollector) Read(interval time.Duration, output chan lp.CC
 			fmt.Sprintf("Read(): Failed to open file '%s': %v", cpuInfoFile, err))
 		return
 	}
-	defer file.Close()
+	defer func() {
+		if err := file.Close(); err != nil {
+			cclog.ComponentError(
+				m.name,
+				fmt.Sprintf("Read(): Failed to close file '%s': %v", cpuInfoFile, err))
+		}
+	}()
 
 	processorCounter := 0
 	now := time.Now()