Fix all staticcheck errors that are not deprecations

ui/controller/controller.go

@@ -2,6 +2,7 @@ package controller
 
 import (
 	"archive/zip"
+	"errors"
 	"fmt"
 	"image"
 	"image/color"
@@ -546,7 +547,7 @@ func (c *Controller) sendNotification(title, content string) {
 
 func (c *Controller) showError(content string) {
 	// TODO: display an in-app toast message instead of a dialog.
-	dialog.ShowError(fmt.Errorf(content), c.MainWindow)
+	dialog.ShowError(errors.New(content), c.MainWindow)
 }
 
 func (c *Controller) ShowAlbumInfoDialog(albumID, albumName string, albumCover image.Image) {

ui/widgets/gridviewitem.go

@@ -378,11 +378,10 @@ func setPlayBtnTranslucency(f float32) {
 
 	// get theme Primary color as color.NRGBA
 	var primary color.NRGBA
-	switch pr := theme.Color(theme.ColorNamePrimary); pr.(type) {
+	switch pr := theme.Color(theme.ColorNamePrimary).(type) {
 	case color.NRGBA:
-		primary = pr.(color.NRGBA)
+		primary = pr
 	case color.RGBA:
-		pr := pr.(color.RGBA)
 		primary = color.NRGBA{R: pr.R, G: pr.G, B: pr.B, A: pr.A}
 	}