// ERROR:  EndLayoutGroup: BeginLayoutGroup must be called first.
        private void Update()
        {
            if (_wantToExportAll)
            {
                _exportTimeout   = 2; // Skip two frames after export...
                _wantToExportAll = false;
                JEMAssetBuilderExporter.ExportPackages(JEMAssetsBuilderConfiguration.GetDirectory(), Packages.ToArray());
            }

            if (_exportPackageOnce)
            {
                _exportTimeout     = 2; // Skip two frames after export...
                _exportPackageOnce = false;
                ExportAssets(_exportPackage);
                _exportPackage = null;
            }
        }
        /// <summary>
        ///     Exports assets of target package.
        /// </summary>
        /// <exception cref="ArgumentNullException"/>
        private static void ExportAssets([NotNull] JEMAssetBuilderPackage package)
        {
            if (package == null)
            {
                throw new ArgumentNullException(nameof(package));
            }
            if (package.Assets.Count == 0)
            {
                EditorUtility.DisplayDialog("Oops.", "Can't export empty package..", "Ok");
            }
            else
            {
                // Before export make sure that all packages are saved, we do not want to lose any data...
                SavePackages();

                // Export!
                JEMAssetBuilderExporter.ExportPackages(JEMAssetsBuilderConfiguration.GetDirectory(), new[] { package });
            }
        }