lint: enable staticcheck and fix problems

.golangci.yml

@@ -8,7 +8,7 @@ linters:
     - ineffassign
     - govet
     - unconvert
-    #- staticcheck
+    - staticcheck
     - gosimple
     - stylecheck
     - unused

s3mem/backend.go

@@ -320,9 +320,9 @@ func (db *Backend) DeleteMulti(ctx context.Context, bucketName string, objects .
 
 		if err != nil {
 			errres := gofakes3.ErrorResultFromError(err)
-			if errres.Code == gofakes3.ErrInternal {
-				// FIXME: log
-			}
+			// if errres.Code == gofakes3.ErrInternal {
+			// 	// FIXME: log
+			// }
 
 			result.Error = append(result.Error, errres)
 

xml/marshal_test.go

@@ -1698,6 +1698,7 @@ func TestMarshal(t *testing.T) {
 }
 
 type AttrParent struct {
+	//nolint:staticcheck // FIXME invalid XML tag: X>Y chain not valid with attr flag
 	X string `xml:"X>Y,attr"`
 }
 
@@ -2494,6 +2495,7 @@ func TestIssue16158(t *testing.T) {
 type InvalidXMLName struct {
 	XMLName Name `xml:"error"`
 	Type    struct {
+		//nolint:staticcheck // FIXME invalid XML tag: cannot use option attr on XMLName field
 		XMLName Name `xml:"type,attr"`
 	}
 }