Idea

I haven't been able to duplicate the error, but I added some more error handling code to handle the situation shown in the error messages you posted. The updated code will release in FlexSim 21.2.3.

If you want to test the updated code to see if it helps right now, you can replace the following nodes' text after loading FlexSim, build all FlexScript, and then try zooming in and out to see if the error goes away.

MAIN:/project/library/GIS/GISNavigator>behaviour/callbacks/downloadTileSuccess

Http.Response response = param(1);
treenode navigator = response.navigator?;
string tileFileName = response.tileFileName?;

if (tileFileName.length > 0)
    response.saveToFile(tileFileName);

if (navigator)
    function_s(navigator, "setMapsDirty", GIS_DIRTY_TILES);

MAIN:/project/library/GIS/GISNavigator>behaviour/callbacks/downloadRouteSuccess

Http.Response response = param(1);
treenode navigator = response.navigator?;
string url = response.url?;
treenode routeNode = response.routeNode?;
treenode pathNode = response.pathNode?;

if (navigator) {
    treenode responseNode = function_s(navigator, "storeWebResponse", url, response.value);
    function_s(navigator, "applyResponseToRoute", responseNode, routeNode, pathNode);
}

The primary change is the addition of the ? in the dynamic property access, which should safely return 0 instead of throwing an exception if something caused those dynamic properties to not work correctly. The if() statements then quietly ignore the message if the properties returned 0.