Panic through internalError on a node kind contained or paths does not list

fejkdata.go

@@ -161,8 +161,9 @@ func paths(n node) []string {
 			out = append(out, p)
 		}
 		return out
+	default:
+		panic(internalError("paths has no case for node %T", n))
 	}
-	return nil
 }
 
 // tablePaths is a table's columns, then each table linked to it under its name: the

graph.go

@@ -73,8 +73,10 @@ func contained(n node) []namedNode {
 			}
 		}
 		return out
-	default:
+	case *nullItem, *tableRow:
 		return nil
+	default:
+		panic(internalError("contained has no case for node %T", n))
 	}
 }
 

render.go

@@ -49,7 +49,8 @@ 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.
+// renderEdges mirrors this switch for the fences. A new node kind goes in every switch
+// that panics through internalError on a kind it does not list.
 func render(s *session, n node, sc renderScope) string {
 	switch n := n.(type) {
 	case *choice:

todo.md

@@ -26,10 +26,6 @@ least modify.
 
 This round, in order:
 
-- Make every switch over node kinds panic through `internalError` on a kind it does not
-  list, as `render` and `renderEdges` do, naming the kinds it skips: `contained` and
-  `paths` return nil. Correct `render`'s "a new node kind goes in both", which misses
-  the rest.
 - Rename the load-time `draw*` types (`drawWalk`, `drawAt`, `drawRoute`, `drawCheck`)
   to say they read and draw nothing, and move `drawWalk` and `tableRead` out of
   `drawfence.go`: a grep for "draw" lands in render and check code alike.