show error when installing an app has failed

lib/app.php

@@ -139,13 +139,18 @@ class OC_App{
 			if(!is_numeric($app)){
 				OC_Installer::installShippedApp($app);
 			}else{
-                                $download=OC_OCSClient::getApplicationDownload($app,1);
-				if(isset($download['downloadlink']) and $download['downloadlink']<>'') {
+				$download=OC_OCSClient::getApplicationDownload($app,1);
+				if(isset($download['downloadlink']) and $download['downloadlink']!='') {
 					$app=OC_Installer::installApp(array('source'=>'http','href'=>$download['downloadlink']));
 				}
 			}
 		}
-		OC_Appconfig::setValue( $app, 'enabled', 'yes' );
+		if($app!==false){
+			OC_Appconfig::setValue( $app, 'enabled', 'yes' );
+			return true;
+		}else{
+			return false;
+		}
 	}
 
 	/**

settings/ajax/disableapp.php

@@ -6,4 +6,4 @@ OC_JSON::setContentTypeHeader();
 
 OC_App::disable($_POST['appid']);
 
-?>
+OC_JSON::success();

settings/ajax/enableapp.php

@@ -5,6 +5,8 @@ require_once('../../lib/base.php');
 OC_JSON::checkAdminUser();
 OC_JSON::setContentTypeHeader();
 
-OC_App::enable($_POST['appid']);
-
-?>
+if(OC_App::enable($_POST['appid'])){
+	OC_JSON::success();
+}else{
+	OC_JSON::error();
+}

settings/js/apps.js

@@ -28,10 +28,18 @@ $(document).ready(function(){
 		var active=$(this).data('active');
 		if(app){
 			if(active){
-				$.post(OC.filePath('settings','ajax','disableapp.php'),{appid:app});
+				$.post(OC.filePath('settings','ajax','disableapp.php'),{appid:app},function(result){
+					if(!result || result.status!='succes'){
+						OC.dialogs.alert('Error','Error while enabling app');
+					}
+				},'json');
 				$('#leftcontent li[data-id="'+app+'"]').removeClass('active');
 			}else{
-				$.post(OC.filePath('settings','ajax','enableapp.php'),{appid:app});
+				$.post(OC.filePath('settings','ajax','enableapp.php'),{appid:app},function(result){
+					if(!result || result.status!='succes'){
+						OC.dialogs.alert('Error','Error while disabling app');
+					}
+				},'json');
 				$('#leftcontent li[data-id="'+app+'"]').addClass('active');
 			}
 			active=!active;