优化结构

internal/data/system/media_upload.go

@@ -75,6 +75,9 @@ func (r *mediaRepo) CreateUploadSession(ctx context.Context, v *system.UploadSes
 func (r *mediaRepo) FindUploadSession(ctx context.Context, id uint) (*system.UploadSession, error) {
 	var po uploadSessionPO
 	if err := r.data.DB().WithContext(ctx).First(&po, id).Error; err != nil {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
+			return nil, system.ErrUploadSessionNotFound
+		}
 		return nil, err
 	}
 	return uploadFromPO(po), nil