Check if OCA.Files.App is available before calling

Signed-off-by: Julius Härtl <jus@bitgrid.net>

apps/files/js/fileactions.js

@@ -671,7 +671,7 @@
 				icon: '',
 				actionHandler: function (filename, context) {
 					var dir = context.$file.attr('data-path') || context.fileList.getCurrentDirectory();
-					if (OCA.Files.App.getActiveView() !== 'files') {
+					if (OCA.Files.App && OCA.Files.App.getActiveView() !== 'files') {
 						OCA.Files.App.setActiveView('files');
 						OCA.Files.App.fileList.changeDirectory(OC.joinPaths(dir, filename), true, true);
 					} else {