Fix AllPlot delete ride crash.

Fixes #431.

src/AllPlot.cpp

@@ -676,7 +676,10 @@ AllPlot::setXTitle()
 void
 AllPlot::setDataFromPlot(AllPlot *plot, int startidx, int stopidx)
 {
-    if (plot == NULL) return;
+    if (plot == NULL) {
+        rideItem = NULL;
+        return;
+    }
 
     referencePlot = plot;
 

src/AllPlotWindow.cpp

@@ -353,6 +353,7 @@ AllPlotWindow::AllPlotWindow(MainWindow *mainWindow) :
     connect(mainWindow, SIGNAL(intervalSelected()), this, SLOT(intervalSelected()));
     connect(mainWindow, SIGNAL(configChanged()), allPlot, SLOT(configChanged()));
     connect(mainWindow, SIGNAL(configChanged()), this, SLOT(configChanged()));
+    connect(mainWindow, SIGNAL(rideDeleted(RideItem*)), this, SLOT(rideDeleted(RideItem*)));
 }
 
 void
@@ -551,6 +552,20 @@ AllPlotWindow::rideSelected()
     stale = false;
 }
 
+void
+AllPlotWindow::rideDeleted(RideItem *ride)
+{
+    if (ride == myRideItem) {
+        // we have nothing to show
+        setProperty("ride", QVariant::fromValue<RideItem*>(NULL));
+
+        // notify all the plots, because when zones are redrawn
+        // they will try and reference AllPlot::rideItem
+        setAllPlotWidgets(NULL);
+        fullPlot->setDataFromRide(NULL);
+    }
+}
+
 void
 AllPlotWindow::zonesChanged()
 {

src/AllPlotWindow.h

@@ -87,6 +87,7 @@ class AllPlotWindow : public GcWindow
 
         // trap GC signals
         void rideSelected();
+        void rideDeleted(RideItem *ride);
         void intervalSelected();
         void zonesChanged();
         void intervalsChanged();