Fix crash when loading project with missing peak controller effect (#4391)

* Fix crash when loading project with missing peak controller effect

* Don't load/save dummy controller connections

src/core/AutomatableModel.cpp

@@ -110,7 +110,8 @@ void AutomatableModel::saveSettings( QDomDocument& doc, QDomElement& element, co
 		element.setAttribute( name, m_value );
 	}
 
-	if( m_controllerConnection )
+	if( m_controllerConnection && m_controllerConnection->getController()->type()
+				!= Controller::DummyController )
 	{
 		QDomElement controllerElement;
 

src/core/ControllerConnection.cpp

@@ -162,6 +162,11 @@ void ControllerConnection::finalizeConnections()
 			c->setController( Engine::getSong()->
 					controllers().at( c->m_controllerId ) );
 		}
+		else if (c->getController()->type() == Controller::DummyController)
+		{
+			delete c;
+			--i;
+		}
 	}
 }
 
@@ -199,7 +204,7 @@ void ControllerConnection::loadSettings( const QDomElement & _this )
 	}
 	else
 	{
-		if( _this.attribute( "id" ).toInt() >= 0 )
+		if( _this.attribute( "id", "-1" ).toInt() >= 0 )
 		{
 			m_controllerId = _this.attribute( "id" ).toInt();
 		}

src/core/Song.cpp

@@ -1122,6 +1122,11 @@ void Song::loadProject( const QString & fileName )
 	// now that everything is loaded
 	ControllerConnection::finalizeConnections();
 
+	// Remove dummy controllers that was added for correct connections
+	m_controllers.erase(std::remove_if(m_controllers.begin(), m_controllers.end(),
+		[](Controller* c){return c->type() == Controller::DummyController;}),
+		m_controllers.end());
+
 	// resolve all IDs so that autoModels are automated
 	AutomationPattern::resolveAllIDs();
 
@@ -1289,9 +1294,13 @@ void Song::restoreControllerStates( const QDomElement & element )
 	while( !node.isNull() && !isCancelled() )
 	{
 		Controller * c = Controller::create( node.toElement(), this );
-		Q_ASSERT( c != NULL );
-
-		addController( c );
+		if (c) {addController(c);}
+		else
+		{
+			// Fix indices to ensure correct connections
+			m_controllers.append(Controller::create(
+				Controller::DummyController, this));
+		}
 
 		node = node.nextSibling();
 	}