Future: errors in labelled graphs?

[harshitmotwani2015]

Workshop-2020-Warwick/AlgebraicStatistics/MLE/StatGraphs.m2

Lines 108 to 134 in d609ee6

	LabeledGraph = new Type of HashTable
	labeledGraph = method(TypicalValue =>LabeledGraph)
	labeledGraph (Digraph,List) := (g,L) -> (
	C := new MutableHashTable;
	C#cache = new CacheTable from {};
	lg := new MutableHashTable;
	lg#graphData = g;
	label := new MutableHashTable;
	if instance(g,Graph) then (
	sg := simpleGraph g;
	scan(L, i ->
	if (sg#graph#(i#0#0))#?(i#0#1) then label#(i#0) = i#1
	else if (sg#graph#(i#0#1))#?(i#0#0) then label#({i#0#1,i#0#0}) = i#1
	else error (toString(i#0)|" is not an edge of the graph");
	);
	)
	else (
	scan(L, i ->
	if (g#graph#(i#0#0))#?(i#0#1) then label#(i#0) = i#1
	else error (toString(i#0)|" is not an edge of the graph");
	);
	);
	lg#labels = new HashTable from label;
	C#graph = lg;
	new LabeledGraph from C
	)

@luisgarciapuente @lukeamendola
I was going through the code of labelled graphs. There are some parts of this code which I think was written for an earlier version of graphs.
I am highlighting parts of code which are not clear to me.

if instance(g,Graph) then (

As the input is digraph I think code will never run the if part

    sg := simpleGraph g;

This is also not working when I use it with digraphs. Instead, if I use underlyingGraph it is working (but in graphs package simpleGraph = underlyingGraph)

I am also wondering if there are any other sections of code in M2 using this labelled graph.