Ensure we cannot create a project with 0 tracks

BUG: 419019

src/dialogs/kdenlivesettingsdialog.cpp

@@ -87,6 +87,16 @@ KdenliveSettingsDialog::KdenliveSettingsDialog(QMap<QString, QString> mappable_a
     m_page8->setIcon(QIcon::fromTheme(QStringLiteral("project-defaults")));
     m_configProject.projecturl->setMode(KFile::Directory);
     m_configProject.projecturl->setUrl(QUrl::fromLocalFile(KdenliveSettings::defaultprojectfolder()));
+    connect(m_configProject.kcfg_videotracks, static_cast<void (QSpinBox::*)(int)>(&QSpinBox::valueChanged), [this]() {
+        if (m_configProject.kcfg_videotracks->value() + m_configProject.kcfg_audiotracks->value() <= 0) {
+            m_configProject.kcfg_videotracks->setValue(1);
+        }
+    });
+    connect(m_configProject.kcfg_audiotracks, static_cast<void (QSpinBox::*)(int)>(&QSpinBox::valueChanged), [this] () {
+        if (m_configProject.kcfg_videotracks->value() + m_configProject.kcfg_audiotracks->value() <= 0) {
+            m_configProject.kcfg_audiotracks->setValue(1);
+        }
+    });
 
     QWidget *p9 = new QWidget;
     m_configProxy.setupUi(p9);

src/project/dialogs/projectsettings.cpp

@@ -92,6 +92,16 @@ ProjectSettings::ProjectSettings(KdenliveDoc *doc, QMap<QString, QString> metada
     connect(generate_imageproxy, &QAbstractButton::toggled, proxy_imageminsize, &QWidget::setEnabled);
     connect(generate_imageproxy, &QAbstractButton::toggled, image_label, &QWidget::setEnabled);
     connect(generate_imageproxy, &QAbstractButton::toggled, proxy_imagesize, &QWidget::setEnabled);
+    connect(video_tracks, static_cast<void (QSpinBox::*)(int)>(&QSpinBox::valueChanged), [this]() {
+        if (video_tracks->value() + audio_tracks->value() <= 0) {
+            video_tracks->setValue(1);
+        }
+    });
+    connect(audio_tracks, static_cast<void (QSpinBox::*)(int)>(&QSpinBox::valueChanged), [this] () {
+        if (video_tracks->value() + audio_tracks->value() <= 0) {
+            audio_tracks->setValue(1);
+        }
+    });
 
     QString currentProf;
     if (doc) {

src/timeline2/view/dialogs/trackdialog.cpp

@@ -32,7 +32,7 @@ TrackDialog::TrackDialog(const std::shared_ptr<TimelineItemModel> &model, int tr
     setWindowTitle(deleteMode ? i18n("Delete Track") : i18n("Add Track"));
     // setFont(QFontDatabase::systemFont(QFontDatabase::SmallestReadableFont));
     setupUi(this);
-    if (m_model->isAudioTrack(m_trackIndex)) {
+    if (m_trackIndex > -1 && m_model->isAudioTrack(m_trackIndex)) {
         audio_track->setChecked(true);
         before_select->setCurrentIndex(1);
     }

src/timeline2/view/timelinecontroller.cpp

@@ -63,7 +63,7 @@ TimelineController::TimelineController(QObject *parent)
     : QObject(parent)
     , m_root(nullptr)
     , m_usePreview(false)
-    , m_activeTrack(0)
+    , m_activeTrack(-1)
     , m_audioRef(-1)
     , m_zone(-1, -1)
     , m_scale(QFontMetrics(QApplication::font()).maxWidth() / 250)