Fix crash on adding first subtitle from subtitle widget

src/core.cpp

@@ -283,10 +283,15 @@ void Core::selectTimelineItem(int id)
     }
 }
 
-std::shared_ptr<SubtitleModel> Core::getSubtitleModel()
+std::shared_ptr<SubtitleModel> Core::getSubtitleModel(bool enforce)
 {
     if (m_guiConstructed && m_mainWindow->getCurrentTimeline()->controller()->getModel()) {
-        return m_mainWindow->getCurrentTimeline()->controller()->getModel()->getSubtitleModel();
+        auto subModel = m_mainWindow->getCurrentTimeline()->controller()->getModel()->getSubtitleModel();
+        if (enforce && subModel == nullptr) {
+            m_mainWindow->slotEditSubtitle();
+            subModel = m_mainWindow->getCurrentTimeline()->controller()->getModel()->getSubtitleModel();
+        }
+        return subModel;
     }
     return nullptr;
 }

src/core.h

@@ -238,7 +238,7 @@ public:
     /** @brief Temporarily un/plug a list of clips in timeline. */
     void temporaryUnplug(QList<int> clipIds, bool hide);
     /** @brief Returns the current doc's subtitle model. */
-    std::shared_ptr<SubtitleModel> getSubtitleModel();
+    std::shared_ptr<SubtitleModel> getSubtitleModel(bool enforce = false);
     
     KSharedDataCache audioThumbCache;
 

src/timeline2/view/timelinecontroller.cpp

@@ -3794,8 +3794,8 @@ void TimelineController::addSubtitle(int startframe)
         startframe = pCore->getTimelinePosition();
     }
     int endframe = startframe + pCore->getDurationFromString(KdenliveSettings::subtitle_duration());
+    auto subtitleModel = pCore->getSubtitleModel(true);
     int id = TimelineModel::getNextId();
-    auto subtitleModel = pCore->getSubtitleModel();
     Fun local_undo = [subtitleModel, id, startframe, endframe]() {
         subtitleModel->removeSubtitle(id);
         pCore->refreshProjectRange({startframe, endframe});