Avoid crash when refreshing style sheet. For some reasons it helps to set and empty stylesheet upfront

src/swiftcore/swiftcore.cpp

@@ -78,13 +78,14 @@ CSwiftCore::~CSwiftCore()
 
 void CSwiftCore::initStyleSheet()
 {
+    if (!sGui || sGui->isShuttingDown()) { return; }
     const QString s = sGui->getStyleSheetUtility().styles(
     {
         CStyleSheetUtility::fileNameFonts(),
         CStyleSheetUtility::fileNameStandardWidget(),
         CStyleSheetUtility::fileNameSwiftCore()
-    }
+    });
-    );
+    this->setStyleSheet(""); // avoid crash, need to reset before
     this->setStyleSheet(s);
 }
 
@@ -104,7 +105,7 @@ void CSwiftCore::showSettingsDialog()
 
 void CSwiftCore::showRawFsdMessageDialog()
 {
-    if(!m_rawFsdMessageDialog)
+    if (!m_rawFsdMessageDialog)
     {
         m_rawFsdMessageDialog.reset(new CRawFsdMessagesDialog(this));
     }

src/swiftlauncher/swiftlauncher.cpp

@@ -180,6 +180,7 @@ void CSwiftLauncher::init()
 
 void CSwiftLauncher::initStyleSheet()
 {
+    if (!sGui || sGui->isShuttingDown()) { return; }
     const QString s = sGui->getStyleSheetUtility().styles(
     {
         CStyleSheetUtility::fileNameFonts(),
@@ -187,6 +188,7 @@ void CSwiftLauncher::initStyleSheet()
         CStyleSheetUtility::fileNameSwiftLauncher()
     }
     );
+    this->setStyleSheet(""); // clear, otherwise launcher crashing
     this->setStyleSheet(s);
 }