Fix failing to change the favourite status of a save crashing the game

I have no idea where the code that used to handle PreviewModelException went but it's pointless anyway; out the window it goes.

src/gui/preview/PreviewController.cpp

@@ -1,7 +1,6 @@
 #include "PreviewController.h"
 #include "Controller.h"
 #include "PreviewModel.h"
-#include "PreviewModelException.h"
 #include "PreviewView.h"
 #include "client/Client.h"
 #include "client/SaveInfo.h"

src/gui/preview/PreviewModel.cpp

@@ -9,7 +9,6 @@
 #include "client/GameSave.h"
 #include "client/SaveInfo.h"
 #include "gui/dialogues/ErrorMessage.h"
-#include "PreviewModelException.h"
 #include "PreviewView.h"
 #include "Config.h"
 #include <cmath>
@@ -244,11 +243,11 @@ void PreviewModel::Update()
 		{
 			if (favouriteSaveRequest->Favourite())
 			{
-				throw PreviewModelException("Error, could not fav. the save: " + ByteString(ex.what()).FromUtf8());
+				new ErrorMessage("Error", "Could not favourite the save: " + ByteString(ex.what()).FromUtf8());
 			}
 			else
 			{
-				throw PreviewModelException("Error, could not unfav. the save: " + ByteString(ex.what()).FromUtf8());
+				new ErrorMessage("Error", "Could not unfavourite the save: " + ByteString(ex.what()).FromUtf8());
 			}
 		}
 		favouriteSaveRequest.reset();

src/gui/preview/PreviewModelException.h

@@ -1,15 +0,0 @@
-#pragma once
-#include "common/String.h"
-#include <exception>
-
-struct PreviewModelException: public std::exception
-{
-	ByteString message;
-public:
-	PreviewModelException(String message_): message(message_.ToUtf8()) {}
-	const char * what() const throw() override
-	{
-		return message.c_str();
-	}
-	~PreviewModelException() throw() {}
-};