Fixed potential crash when layer is instantiated without specifying a provider key.

git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@7262 c8812cc2-4d05-0410-92ff-de0c093fc19c

Author: wonder

src/core/qgsvectorlayer.cpp

@@ -88,6 +88,7 @@ QgsVectorLayer::QgsVectorLayer(QString vectorLayerPath,
     QString providerKey)
 : QgsMapLayer(VECTOR, baseName, vectorLayerPath),
   mUpdateThreshold(0),       // XXX better default value?
+  mDataProvider(NULL),
   mProviderKey(providerKey),
   mEditable(false),
   mModified(false),