Fix audio bug

vendor/github.com/veandco/go-sdl2/mix/sdl_mixer.go

@@ -37,9 +37,12 @@ package mix
 //}
 //#endif
 import "C"
-import "unsafe"
-import "reflect"
-import "github.com/veandco/go-sdl2/sdl"
+import (
+	"reflect"
+	"unsafe"
+
+	"github.com/veandco/go-sdl2/sdl"
+)
 
 // Chunk is the internal format for an audio chunk.
 // (https://www.libsdl.org/projects/SDL_mixer/docs/SDL_mixer_85.html)
@@ -212,6 +215,7 @@ func LoadWAV(file string) (chunk *Chunk, err error) {
 	chunk = (*Chunk)(unsafe.Pointer(C.Mix_LoadWAV_RW(C.SDL_RWFromFile(_file, _rb), 1)))
 	if chunk == nil {
 		err = sdl.GetError()
+		return nil, err
 	}
 	return
 }
@@ -224,6 +228,7 @@ func LoadMUS(file string) (mus *Music, err error) {
 	mus = (*Music)(unsafe.Pointer(C.Mix_LoadMUS(_file)))
 	if mus == nil {
 		err = sdl.GetError()
+		return nil, err
 	}
 	return
 }