I'm running into a similar issue configuring a pop up in a web map in my organization's AGOL account.
The issue I'm running into is actually in a web app that uses the web map. The error doesn't pop up until I try to view or export data from the attribute table widget.
The issue seems to relate to accessing attributes of the geometry object.
The following code causes the error:
// Convert Lines/Polygons to Points
var PointGeometry = Centroid(Geometry($feature));
var pointX = PointGeometry.x;
var pointY = PointGeometry.y;
return (text(pointX) + ":" + text(pointY);
While this does not:
// Convert Lines/Polygons to Points
var PointGeometry = Centroid(Geometry($feature));
return (text(PointGeometry));
Have you had any luck resolving this issue?