FIx possible startup crash

src/monitor/glwidget.cpp

@@ -644,6 +644,11 @@ void GLWidget::updateRulerHeight(int addedHeight)
     resizeGL(width(), height());
 }
 
+bool GLWidget::isReady() const
+{
+    return m_consumer != nullptr;
+}
+
 void GLWidget::requestSeek(int position)
 {
     m_consumer->set("scrub_audio", 1);

src/monitor/glwidget.h

@@ -140,6 +140,8 @@ public:
     void purgeCache();
     /** @brief Show / hide monitor ruler */
     void switchRuler(bool show);
+    /** @brief Returns true if consumer is initialized */
+    bool isReady() const;
 
 protected:
     void mouseReleaseEvent(QMouseEvent *event) override;

src/monitor/monitor.cpp

@@ -1421,6 +1421,9 @@ void Monitor::forceMonitorRefresh()
 
 void Monitor::refreshMonitorIfActive(bool directUpdate)
 {
+    if (!m_glMonitor->isReady()) {
+        return;
+    }
     if (isActive()) {
         if (directUpdate) {
             m_glMonitor->refresh();