Summary

Fixes a panic with an unrouted edge to a grid cell that is a container.

Details

• fixes Error with connection to grid cell container #1719
• for grid cells that are containers, external edge object references(pointers) were not updated after layout
• this caused grid layout to incorrectly skip routing for the cell-cell edge, leading to an empty route and a panic during rendering
• fixed by updating the object references used for grid cell containers after running layout
• this wouldn't occur with dagre/elk but would occur with TALA or other plugins that don't return the exact same *d2graph.Object from Layout