enabled and fixed the errcheck linter rule

pkg/systemlogmonitor/logwatchers/filelog/log_watcher.go

@@ -91,7 +91,9 @@ const watchPollInterval = 500 * time.Millisecond
 // watchLoop is the main watch loop of filelog watcher.
 func (s *filelogWatcher) watchLoop() {
 	defer func() {
-		s.closer.Close()
+		if err := s.closer.Close(); err != nil {
+			klog.Errorf("Failed to close log file: %v", err)
+		}
 		close(s.logCh)
 		s.tomb.Done()
 	}()

pkg/systemlogmonitor/logwatchers/filelog/log_watcher_test.go

@@ -141,8 +141,12 @@ Jan  2 03:04:05 kernel: [2.000000] 3
 		f, err := os.CreateTemp("", "log_watcher_test")
 		assert.NoError(t, err)
 		defer func() {
-			f.Close()
-			os.Remove(f.Name())
+			if err := f.Close(); err != nil {
+				t.Logf("failed to close temporary file %s: %v", f.Name(), err)
+			}
+			if err := os.Remove(f.Name()); err != nil {
+				t.Logf("failed to remove temporary file %s: %v", f.Name(), err)
+			}
 		}()
 		_, err = f.Write([]byte(test.log))
 		assert.NoError(t, err)

pkg/systemlogmonitor/logwatchers/kmsg/log_watcher_linux.go

@@ -77,7 +77,9 @@ func (k *kernelLogWatcher) Watch() (<-chan *logtypes.Log, error) {
 
 // Stop closes the kmsgparser
 func (k *kernelLogWatcher) Stop() {
-	k.kmsgParser.Close()
+	if err := k.kmsgParser.Close(); err != nil {
+		klog.Errorf("Failed to close kmsg parser: %v", err)
+	}
 	k.tomb.Stop()
 }