Use QSaveFile wherever applicable

expected.hpp was fetched from:
b803e3c07b/include/nonstd/expected.hpp

src/app/filelogger.cpp

@@ -179,7 +179,7 @@ void FileLogger::openLogFile()
 {
     if (!m_logFile.open(QIODevice::WriteOnly | QIODevice::Append | QIODevice::Text)
         || !m_logFile.setPermissions(QFile::ReadOwner | QFile::WriteOwner))
-        {
+    {
         m_logFile.close();
         LogMsg(tr("An error occurred while trying to open the log file. Logging to file is disabled."), Log::CRITICAL);
     }