GraphEdgeCollection.edge returns undefined

[Hunter21007]

If i try to get an edge by its _id

let edges: GraphEdgeCollection;
const tEd = await edges.edge(sr._id);

then the result is undefined

as in source

arangojs/src/graph.ts

Line 113 in 44a6968

async edge(documentHandle: DocumentHandle) {

the function returns

arangojs/src/graph.ts

Line 117 in 44a6968

return res.body.graph;

in debugger res.body contains an edge, but no graph

Do i something wrong?

arangojs version: 6.0.1
arangodb version 3.2.3
nodejs version: 8.9.4
vscode: 1.9.2

[Hunter21007]

BTW: EdgeCollection.edge returns res.body

arangojs/src/collection.ts

Line 523 in 44a6968

return res.body;