topology checker: catch difference error (fixes #7845)

jef-n · jef-n · commit 454778c7a5e0 · 2013-07-21T10:15:44.000+02:00
diff --git a/src/plugins/topology/topolTest.cpp b/src/plugins/topology/topolTest.cpp
@@ -694,6 +694,11 @@ ErrorList topolTest::checkGaps( double tolerance, QgsVectorLayer *layer1, QgsVec
   //qDebug() << "extent wkt - " << bufferExtent->exportToWkt();
 
   QgsGeometry* diffGeoms = bufferExtent->difference( &test );
+  if ( !diffGeoms )
+  {
+    qDebug() << "difference result 0-";
+    return errorList;
+  }
 
   //qDebug() << "difference gometry - " << diffGeoms->exportToWkt() ;
 
