gui: Begin simple IPC error reporting

gui/ipcpreviewclient.cpp

@@ -61,7 +61,8 @@ void IPCPreviewClient::start(RenderConfig config, const QVector<RenderTarget> &t
 
 	if(!connect() || !socket->isOpen())
 	{
-		// TODO: ERROR
+		emit error("Could not connect to IPC worker");
+		return;
 	}
 
 	if(socket->isOpen() && socket->isWritable())
@@ -88,7 +89,8 @@ void IPCPreviewClient::start(RenderConfig config, const QVector<RenderTarget> &t
 		}
 		else
 		{
-			// TODO: ERROR
+			emit error("Error while trying to process previews: " + socket->errorString());
+			return;
 		}
 
 		int processed = 0;
@@ -107,7 +109,7 @@ void IPCPreviewClient::start(RenderConfig config, const QVector<RenderTarget> &t
 		}
 		if(processed != targets.count())
 		{
-			// TODO: ERROR
+			emit error("IPC worker didn't send enough previews. This is a bug, please report");
 		}
 	}
 	socket->disconnectFromServer();
@@ -118,7 +120,8 @@ void IPCPreviewClient::stopGeneration()
 {
 	if(!connect() || !socket->isOpen())
 	{
-		// TODO: ERROR
+		emit error("Could not connect to IPC worker");
+		return;
 	}
 	QDataStream stream(socket);
 	stream << StopGeneratePreviews;

gui/ipcpreviewclient.h

@@ -31,6 +31,7 @@ class IPCPreviewClient : public QObject
   signals:
 	void previewReceived(QSharedPointer<PreviewResult> previewResult, unsigned int currentPreviewGeneration);
 	void finished();
+	void error(QString);
 };
 
 #endif // IPCPREVIEWCLIENT_H

gui/mainwindow.cpp

@@ -34,6 +34,12 @@ MainWindow::MainWindow(QWidget *parent, QString socketPath) : QMainWindow(parent
 			Qt::QueuedConnection);
 	connect(&ipcPreviewClient, &IPCPreviewClient::finished, this,
 			[&] { this->ui->previewProcessBar->setValue(this->ui->previewProcessBar->maximum()); });
+	connect(&ipcPreviewClient, &IPCPreviewClient::error, this,
+			[this](QString msg)
+			{
+				qCritical() << msg << Qt::endl;
+				QMessageBox::critical(this, "IPC error", msg);
+			});
 
 	connect(this, &MainWindow::startIpcPreviews, &ipcPreviewClient, &IPCPreviewClient::startGeneration,
 			Qt::QueuedConnection);