CSE Machine: Overlapping drawing of pairs

[deseansoh]

When running the following code and attempting to display the environmental model in the CSE machine, the pairs constructed overlap with one another. The arrows are pointing correctly though.

const hh1 = pair(undefined, undefined);
const hh2 = pair(undefined, undefined);
const hh3 = pair(undefined, undefined);

set_head(hh1, hh1);
set_tail(hh1, hh1);

set_head(hh2, pair(undefined, hh2));
set_head(head(hh2), head(hh2));
set_tail(hh2, hh2);

set_head(hh3, pair(hh3,hh3));
set_tail(hh3, head(hh3));

[martin-henz]

I can confirm that the bug exists. Here is the share link:
https://share.sourceacademy.org/t5pi8