fix crash when x3d is empty

code/AssetLib/Collada/ColladaParser.cpp

@@ -118,14 +118,16 @@ ColladaParser::ColladaParser(IOSystem *pIOHandler, const std::string &pFile) :
     }
 
     // generate a XML reader for it
-    ;
     if (!mXmlParser.parse(daefile.get())) {
         ThrowException("Unable to read file, malformed XML");
     }
     // start reading
     XmlNode node = mXmlParser.getRootNode();
-    std::string name = node.name();
-    ReadContents(node);
+    XmlNode colladaNode = node.child("COLLADA");
+    if (colladaNode.empty()) {
+        return;
+    }
+    ReadContents(colladaNode);
 
     // read embedded textures
     if (zip_archive && zip_archive->isOpen()) {

code/AssetLib/X3D/X3DImporter.cpp

@@ -194,6 +194,8 @@ void X3DImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
     pIOHandler->PushDirectory(slashPos == std::string::npos ? std::string() : pFile.substr(0, slashPos + 1));
     ParseFile(pFile, pIOHandler);
     pIOHandler->PopDirectory();
+    if (NodeElement_List.empty())
+        return;
     //
     // Assimp use static arrays of objects for fast speed of rendering. That's good, but need some additional operations/
     // We know that geometry objects(meshes) are stored in <Shape>, also in <Shape>-><Appearance> materials(in Assimp logical view)