Summary: Clicking on a polygon with a node selected and the POI Info or Graph Info tabs on the right panel open will crash the site.
Likely Explanation: The POI Info and Graph Info tabs on the right panel are only meant to be used when a node is selected. When a polygon is selected, these tabs do not exist. Therefore, switching from a node with either tab open to a polygon will cause a fatal crash.
Workaround: Make sure the right panel is on the Room Info tab before switching from nodes to polygons.