PdfProcessor: Exception instead of empty result when loading of document fails

cli/pdfprocessor.cpp

@@ -13,7 +13,7 @@ QVector<PageData> PdfProcessor::process(const QByteArray &data) const
     QScopedPointer<Poppler::Document> doc(Poppler::Document::loadFromData(data));
     if(doc.isNull())
     {
-        return { };
+        throw QSSGeneralException("Failed to process pdf data");
     }
     QRectF entirePage;