Fix startup crash introduced in last commit

src/capture/mediacapture.cpp

@@ -41,7 +41,6 @@ MediaCapture::MediaCapture(QObject *parent)
     m_resetTimer.setInterval(5000);
     m_resetTimer.setSingleShot(true);
     connect(&m_resetTimer, &QTimer::timeout, this, &MediaCapture::resetIfUnused);
-    connect(pCore->mixer(), &MixerManager::updateRecVolume, this, &MediaCapture::setAudioVolume);
 }
 
 MediaCapture::~MediaCapture() = default;

src/core.cpp

@@ -183,6 +183,7 @@ void Core::initGUI(const QUrl &Url, const QString &clipsToLoad)
     connect(m_library, SIGNAL(addProjectClips(QList<QUrl>)), m_binWidget, SLOT(droppedUrls(QList<QUrl>)));
     connect(this, &Core::updateLibraryPath, m_library, &LibraryWidget::slotUpdateLibraryPath);
     connect(m_capture.get(), &MediaCapture::recordStateChanged, m_mixerWidget, &MixerManager::recordStateChanged);
+    connect(m_mixerWidget, &MixerManager::updateRecVolume, m_capture.get(), &MediaCapture::setAudioVolume);
     m_monitorManager = new MonitorManager(this);
     connect(m_monitorManager, &MonitorManager::cleanMixer, m_mixerWidget, &MixerManager::clearMixers);
     // Producer queue, creating MLT::Producers on request