Add staticcheck to CI steps

.drone.yml

@@ -8,6 +8,8 @@ steps:
   image: golang:1.17
   commands:
     - cd backend/
+    - go install honnef.co/go/tools/cmd/staticcheck@latest
     - go build ./...
     - go vet ./...
+    - staticcheck ./...
     - go test -bench=. -benchmem -cover ./...

backend/filestore/fs.go

@@ -54,7 +54,7 @@ func (s *FileSystemStore) GetObjectWithRange(ctx context.Context, key string, st
 	if err != nil {
 		return nil, fmt.Errorf("error opening file: %v", err)
 	}
-	_, err = fptr.Seek(start, os.SEEK_SET)
+	_, err = fptr.Seek(start, io.SeekStart)
 	if err != nil {
 		return nil, fmt.Errorf("error seeking in file: %v", err)
 	}

backend/media/service.go

@@ -20,11 +20,6 @@ import (
 	"go.uber.org/zap"
 )
 
-const (
-	getVideoExpiresIn = time.Hour
-	getAudioExpiresIn = time.Hour
-)
-
 const (
 	rawAudioCodec      = "pcm_s16le"
 	rawAudioFormat     = "s16le"
@@ -578,7 +573,6 @@ func (s *MediaSetService) getThumbnailFromYoutube(ctx context.Context, mediaSet
 type progressReader struct {
 	io.Reader
 
-	label      string
 	total, exp int64
 	logger     *zap.SugaredLogger
 }