fix merge

tinyxml2.cpp

@@ -2348,11 +2348,10 @@ static FILE* callfopen( const char* filepath, const char* mode )
 }
 
 void XMLDocument::DeleteNode( XMLNode* node )	{   
-    TIXMLASSERT( node );
-    TIXMLASSERT(node->_document == this );
     if(node == 0) {
         return; // check for null pointer
     }
+    TIXMLASSERT(node->_document == this);
     if (node->_parent) {
         node->_parent->DeleteChild( node );
     }