fix control may reach end of non void function

agui2/src/Graphics/Dialogs/OutputDialog.cpp

@@ -105,7 +105,7 @@ TabType OutputDialog::getCurrentTabType() const {
         return TabType::Image;
     }
-    Q_ASSERT(false);
+    throw std::logic_error ( "Invalid tab type" );
 }
 std::pair<QString, QString> OutputDialog::getCurrentTabFileFilter() const {
@@ -115,5 +115,5 @@ std::pair<QString, QString> OutputDialog::getCurrentTabFileFilter() const {
         case TabType::DOT: return { "DOT files (*.dot)", ".dot" };
         case TabType::Image: return { "PNG files (*.png)", ".png" };
     }
-    Q_ASSERT(false);
+    throw std::logic_error ( "Invalid tab type" );
 }