Update staticcheck version and fix all warnings (#1381)

pkg/fetcher/config/config.go

@@ -7,8 +7,7 @@ import (
 	"os"
 	"path/filepath"
 
-	"github.com/fission/fission/pkg/types"
-	"github.com/fission/fission/pkg/utils"
+	"github.com/pkg/errors"
 	apiv1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/resource"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -16,6 +15,8 @@ import (
 	"k8s.io/client-go/kubernetes"
 
 	fv1 "github.com/fission/fission/pkg/apis/fission.io/v1"
+	"github.com/fission/fission/pkg/types"
+	"github.com/fission/fission/pkg/utils"
 )
 
 type Config struct {
@@ -30,9 +31,9 @@ type Config struct {
 	sharedSecretPath string
 	sharedCfgMapPath string
 
-	dockerRegistryAuthDomain string
-	dockerRegistryUsername   string
-	dockerRegistryPassword   string
+	// dockerRegistryAuthDomain string
+	// dockerRegistryUsername   string
+	// dockerRegistryPassword   string
 
 	serviceAccount string
 
@@ -289,7 +290,7 @@ func (cfg *Config) addFetcherToPodSpecWithCommand(podSpec *apiv1.PodSpec, mainCo
 		for _, existingContainer := range podSpec.Containers {
 			existingContainerNames = append(existingContainerNames, existingContainer.Name)
 		}
-		return fmt.Errorf("Could not find main container '%s' in given PodSpec. Found: %v",
+		return errors.Errorf("could not find main container '%s' in given PodSpec. Found: %v",
 			mainContainerName,
 			existingContainerNames)
 	}

pkg/fetcher/fetcher.go

@@ -151,7 +151,7 @@ func writeSecretOrConfigMap(dataMap map[string][]byte, dirPath string) error {
 
 func (fetcher *Fetcher) VersionHandler(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "application/json; charset=utf-8")
-	fmt.Fprintf(w, info.BuildInfo().String())
+	w.Write([]byte(info.BuildInfo().String()))
 }
 
 func (fetcher *Fetcher) FetchHandler(w http.ResponseWriter, r *http.Request) {