Fix all staticcheck errors that are not deprecations

backend/cmdlineoptions.go

@@ -58,9 +58,7 @@ func init() {
 		return err
 	})
 	flag.Func("volume-adjust-pct", "adjusts volume up or down by the given percentage (positive or negative)", func(s string) error {
-		if strings.HasSuffix(s, "%") {
-			s = s[:len(s)-1]
-		}
+		s = strings.TrimSuffix(s, "%")
 		v, err := strconv.ParseFloat(s, 64)
 		VolumePctCLIArg = v
 		return err

backend/mediaprovider/subsonic/artistiterator.go

@@ -22,11 +22,8 @@ func (s *subsonicMediaProvider) ArtistSortOrders() []string {
 	}
 }
 
-func filterArtistMatches(f mediaprovider.ArtistFilter, artist *subsonic.ArtistID3) bool {
-	if artist == nil {
-		return false
-	}
-	return true
+func filterArtistMatches(_ mediaprovider.ArtistFilter, artist *subsonic.ArtistID3) bool {
+	return artist != nil
 }
 
 func (s *subsonicMediaProvider) IterateArtists(sortOrder string, filter mediaprovider.ArtistFilter) mediaprovider.ArtistIterator {
@@ -176,9 +173,7 @@ func (s *subsonicMediaProvider) artistFetchFnFromStandardSort(sortFn func([]*sub
 		}
 		var artists []*subsonic.ArtistID3
 		for _, idx := range idxs.Index {
-			for _, ar := range idx.Artist {
-				artists = append(artists, ar)
-			}
+			artists = append(artists, idx.Artist...)
 		}
 		artists = sortFn(artists)
 		return artists, nil

backend/windows/smtc_unsupported.go

@@ -24,18 +24,18 @@ const (
 
 type SMTC struct{}
 
-var smtcUnsupportedErr = errors.New("SMTC is not supported on this platformo")
+var errSMTCUnsupported = errors.New("no support for SMTC on this platform")
 
 func InitSMTCForWindow(hwnd uintptr) (*SMTC, error) {
-	return nil, smtcUnsupportedErr
+	return nil, errSMTCUnsupported
 }
 
 func (s *SMTC) SetEnabled(enabled bool) error {
-	return smtcUnsupportedErr
+	return errSMTCUnsupported
 }
 
 func (s *SMTC) SetThumbnail(filepath string) error {
-	return smtcUnsupportedErr
+	return errSMTCUnsupported
 }
 
 func (s *SMTC) OnButtonPressed(func(SMTCButton)) {}
@@ -45,13 +45,13 @@ func (s *SMTC) OnSeek(f func(millis int)) {}
 func (s *SMTC) Shutdown() {}
 
 func (s *SMTC) UpdatePlaybackState(state SMTCPlaybackState) error {
-	return smtcUnsupportedErr
+	return errSMTCUnsupported
 }
 
 func (s *SMTC) UpdateMetadata(title, artist string) error {
-	return smtcUnsupportedErr
+	return errSMTCUnsupported
 }
 
 func (s *SMTC) UpdatePosition(positionMillis, durationMillis int) error {
-	return smtcUnsupportedErr
+	return errSMTCUnsupported
 }