null check uses of CommonTrackPanelCell::FindTrack

src/tracks/playabletrack/notetrack/ui/NoteTrackControls.cpp

@@ -151,7 +151,7 @@ HitTestResult NoteTrackControls::HitTest
    const wxRect &rect = evt.rect;
    if (event.ButtonDown() || event.ButtonDClick()) {
       auto track = FindTrack();
-      if (track->GetKind() == Track::Note) {
+      if (track && track->GetKind() == Track::Note) {
          HitTestResult result;
          if (NULL !=
              (result = MuteButtonHandle::HitTest

src/tracks/playabletrack/wavetrack/ui/WaveTrackControls.cpp

@@ -61,7 +61,7 @@ HitTestResult WaveTrackControls::HitTest
    const wxRect &rect = evt.rect;
    if (event.Button(wxMOUSE_BTN_LEFT)) {
       auto track = FindTrack();
-      if (track->GetKind() == Track::Wave) {
+      if (track && track->GetKind() == Track::Wave) {
          HitTestResult result;
          if (NULL !=
              (result = MuteButtonHandle::HitTest

src/tracks/playabletrack/wavetrack/ui/WaveTrackVRulerControls.cpp

@@ -675,6 +675,8 @@ unsigned WaveTrackVRulerControls::HandleWheelRotation
    evt.event.Skip(false);
 
    Track *const pTrack = FindTrack();
+   if (!pTrack)
+      return RefreshNone;
    wxASSERT(pTrack->GetKind() == Track::Wave);
    auto steps = evt.steps;
 

src/tracks/ui/ButtonHandle.cpp

@@ -38,15 +38,19 @@ HitTestPreview ButtonHandle::HitPreview()
 UIHandle::Result ButtonHandle::Click
 (const TrackPanelMouseEvent &evt, AudacityProject *)
 {
-   const wxMouseEvent &event = evt.event;
    using namespace RefreshCode;
+   auto pTrack = Track::Pointer(
+      static_cast<TrackControls*>(evt.pCell)->FindTrack() );
+   if ( !pTrack )
+      return Cancelled;
+
+   const wxMouseEvent &event = evt.event;
    if (!event.Button(wxMOUSE_BTN_LEFT))
       return Cancelled;
 
    // Come here for left click or double click
    if (mRect.Contains(event.m_x, event.m_y)) {
-      mpTrack = Track::Pointer(
-         static_cast<TrackControls*>(evt.pCell)->FindTrack() );
+      mpTrack = pTrack;
       TrackControls::gCaptureState = mDragCode;
       // Toggle visible button state
       return RefreshCell;

src/tracks/ui/SelectHandle.cpp

@@ -808,35 +808,35 @@ UIHandle::Result SelectHandle::Drag
          return RefreshNone;
    }
 
-   Track *clickedTrack =
-      static_cast<CommonTrackPanelCell*>(evt.pCell)->FindTrack();
-
-   // Handle which tracks are selected
-   Track *sTrack = pTrack.get();
-   Track *eTrack = clickedTrack;
-   auto trackList = pProject->GetTracks();
-   auto pMixerBoard = pProject->GetMixerBoard();
-   if ( sTrack && eTrack && !event.ControlDown() ) {
-      auto &selectionState = pProject->GetSelectionState();
-      selectionState.SelectRangeOfTracks
+   if ( auto clickedTrack =
+       static_cast<CommonTrackPanelCell*>(evt.pCell)->FindTrack() ) {
+      // Handle which tracks are selected
+      Track *sTrack = pTrack.get();
+      Track *eTrack = clickedTrack;
+      auto trackList = pProject->GetTracks();
+      auto pMixerBoard = pProject->GetMixerBoard();
+      if ( sTrack && eTrack && !event.ControlDown() ) {
+         auto &selectionState = pProject->GetSelectionState();
+         selectionState.SelectRangeOfTracks
          ( *trackList, *sTrack, *eTrack, pMixerBoard );
-   }
+      }
 
 #ifdef EXPERIMENTAL_SPECTRAL_EDITING
 #ifndef SPECTRAL_EDITING_ESC_KEY
-   if (mFreqSelMode == FREQ_SEL_SNAPPING_CENTER &&
-      !viewInfo.selectedRegion.isPoint())
-      MoveSnappingFreqSelection
+      if (mFreqSelMode == FREQ_SEL_SNAPPING_CENTER &&
+          !viewInfo.selectedRegion.isPoint())
+         MoveSnappingFreqSelection
          (pProject, viewInfo, y, mRect.y, mRect.height, pTrack.get());
-   else
+      else
 #endif
-      if (mFreqSelTrack.lock() == pTrack)
-         AdjustFreqSelection(
-            static_cast<WaveTrack*>(pTrack.get()),
-            viewInfo, y, mRect.y, mRect.height);
+         if (mFreqSelTrack.lock() == pTrack)
+            AdjustFreqSelection(
+                                static_cast<WaveTrack*>(pTrack.get()),
+                                viewInfo, y, mRect.y, mRect.height);
 #endif
-
-   AdjustSelection(viewInfo, x, mRect.x, clickedTrack);
+      
+      AdjustSelection(viewInfo, x, mRect.x, clickedTrack);
+   }
 
    return RefreshNone
 

src/tracks/ui/TrackControls.cpp

@@ -203,6 +203,9 @@ unsigned TrackControls::DoContextMenu
    TrackInfo::GetTitleBarRect(rect, buttonRect);
 
    auto track = FindTrack();
+   if (!track)
+      return RefreshCode::RefreshNone;
+
    InitMenuData data{ track, pParent, RefreshCode::RefreshNone };
 
    const auto pTable = &TrackMenuTable::Instance();

src/tracks/ui/TrackSelectHandle.cpp

@@ -96,6 +96,8 @@ UIHandle::Result TrackSelectHandle::Click
 
    TrackControls *const pControls = static_cast<TrackControls*>(evt.pCell);
    Track *const pTrack = pControls->FindTrack();
+   if (!pTrack)
+      return Cancelled;
    TrackPanel *const trackPanel = pProject->GetTrackPanel();
    const bool unsafe = pProject->IsAudioActive();