Make renderEdges panic on a node kind it does not handle, and drop the done round item

graph.go

@@ -114,7 +114,7 @@ func (e renderEdge) reached() string {
 	return "{" + e.label + "}"
 }
 
-// renderEdges lists the children rendering n recurses into, mirroring expand: a
+// renderEdges lists the children rendering n recurses into, mirroring render: a
 // choice's items, and a template's field/reference tokens plus its operands. A
 // folder renders nothing, so it has no edges.
 func renderEdges(n node) []renderEdge {
@@ -155,8 +155,10 @@ func renderEdges(n node) []renderEdge {
 			es = append(es, renderEdge{to: c.node, label: n.t.header[n.i]})
 		}
 		return es
-	default:
+	case *folder, *nullItem:
 		return nil
+	default:
+		panic(fmt.Sprintf("fejkdata: renderEdges has no case for node %T", n))
 	}
 }
 

render.go

@@ -49,6 +49,7 @@ func descend(s *session, root node, segments []string, sc renderScope) (node, er
 // render evaluates a compiled node to a string. compile validates every node up
 // front, so rendering a compiled tree cannot fail. sc holds the reference draws the
 // render shares; each repeat iteration renders over a hold set of its own.
+// renderEdges mirrors this switch for the fences, so a new node kind goes in both.
 func render(s *session, n node, sc renderScope) string {
 	switch n := n.(type) {
 	case *choice:

todo.md

@@ -23,9 +23,6 @@ Shape 5.8, Self-sufficiency 5.7), every seat capped by Locality, all nine naming
 
 This round, in order:
 
-- Make `renderEdges` panic on a node it does not handle, as `render` does: its
-  `default: return nil` silently exempts a new node kind from every fence, and nothing
-  at `expand` says `renderEdges` mirrors it.
 - Carry the arm on `renderEdge` so `graph.go`, `drawfence.go` and `holdfence.go` stop
   re-parsing `label` through `splitArm`, whose key differs before and after link.
 - Give `pathCover` a doc comment and say in each path walk's comment how it differs from