ReadAsArray leaves Qgs in unstable state

I have a QGIS plugin that reads a raster to get the elevation at vertex points in a polyline. The issue is that even though a single call to ReadAsArray(…) appears to work, if I immediately exit QGIS, A Crash Dump dialog appears. What is wrong with the way I making the call?

def run(self):   
# show the dialog
self.dlg.show()
# Run the dialog event loop
result = self.dlg.exec_()
# See if OK was pressed
if result:
    selectedVectorLayer = self.getSelectedVectorLayer()
    selectedRasterLayer = self.getSelectedRasterLayer()
    if self.validateSelectedLayers(selectedVectorLayer,selectedRasterLayer) is False:
        return;         
    gdal.AllRegister()        
    ds = gdal.Open(selectedRasterLayer.source(), GA_ReadOnly)
    if ds is None:
        QgsMessageLog.logMessage(selectedRasterLayer.source() + ' not found!', 'LineSlopes', QgsMessageLog.WARNING) 
        return   
    dataPoint = ds.GetRasterBand(1).ReadAsArray(122, 149, 1, 1)
    del ds