Road graph plugin: don't crash with 25D input layers

Fix #9174

Author: m-kuhn

src/analysis/network/qgslinevectorlayerdirector.cpp

@@ -166,9 +166,11 @@ void QgsLineVectorLayerDirector::makeGraph( QgsGraphBuilderInterface *builder, c
   while ( fit.nextFeature( feature ) )
   {
     QgsMultiPolyline mpl;
-    if ( feature.geometry()->wkbType() == QGis::WKBMultiLineString )
+    if ( feature.geometry()->wkbType() == QGis::WKBMultiLineString
+         || feature.geometry()->wkbType() == QGis::WKBMultiLineString25D )
       mpl = feature.geometry()->asMultiPolyline();
-    else if ( feature.geometry()->wkbType() == QGis::WKBLineString )
+    else if ( feature.geometry()->wkbType() == QGis::WKBLineString
+              || feature.geometry()->wkbType() == QGis::WKBLineString25D )
       mpl.push_back( feature.geometry()->asPolyline() );
 
     QgsMultiPolyline::iterator mplIt;

src/plugins/roadgraph/shortestpathwidget.cpp

@@ -37,6 +37,7 @@
 #include <qgsfeature.h>
 #include <qgsapplication.h>
 #include <qgsvectorlayer.h>
+#include <qgsmessagebar.h>
 
 #include <qgsgraphdirector.h>
 #include <qgsgraphbuilder.h>
@@ -278,17 +279,27 @@ QgsGraph* RgShortestPathWidget::getPath( QgsPoint& p1, QgsPoint& p2 )
 
   QgsGraph *graph = builder.graph();
 
-  QVector< int > pointIdx( 0, 0 );
-  QVector< double > pointCost( 0, 0.0 );
-
   int startVertexIdx = graph->findVertex( p1 );
 
   int criterionNum = 0;
   if ( mCriterionName->currentIndex() > 0 )
     criterionNum = 1;
 
-  QgsGraph* shortestpathTree = QgsGraphAnalyzer::shortestTree( graph, startVertexIdx, criterionNum );
+  if ( graph->vertexCount() == 0 )
+  {
+    mPlugin->iface()->messageBar()->pushMessage(
+      tr( "Cannot calculate path" ),
+      tr( "The graph is empty. Does the layer have a supported geometry type?" ),
+      QgsMessageBar::WARNING,
+      mPlugin->iface()->messageTimeout()
+    );
+
+    delete graph;
+    return NULL;
+  }
+
 
+  QgsGraph* shortestpathTree = QgsGraphAnalyzer::shortestTree( graph, startVertexIdx, criterionNum );
   delete graph;
 
   if ( shortestpathTree->findVertex( p2 ) == -1 )