Universe does not install

[axiomtutor]

Using Linux Mint 19.1, with OPAM version 2.0.5, OCaml version 4.09.0, I tried to install the Universe library. When I try I get the following errors that I don't know how to resolve.

The following actions will be performed:
  ∗ install conf-cairo       1      [required by cairo2, cairo2-gtk]
  ∗ install conf-gnomecanvas 2      [required by universe]
  ∗ install cairo2           0.6.1  [required by universe]
  ∗ install lablgtk          2.18.8 [required by universe]
  ∗ install cairo2-gtk       0.6.1  [required by universe]
  ∗ install universe         0.0*
===== ∗ 6 =====
Do you want to continue? [Y/n] y

<><> Gathering sources ><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
[cairo2.0.6.1] found in cache
[cairo2-gtk.0.6.1] found in cache
[lablgtk.2.18.8] found in cache

<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
[ERROR] The compilation of conf-cairo failed at
        "/home/username/.opam/opam-init/hooks/sandbox.sh build pkg-config cairo".
[ERROR] The compilation of conf-gnomecanvas failed at
        "/home/username/.opam/opam-init/hooks/sandbox.sh build pkg-config
        libgnomecanvas-2.0".

#=== ERROR while compiling conf-gnomecanvas.2 =================================#
# context     2.0.5 | linux/x86_64 | ocaml-base-compiler.4.09.0 | https://opam.ocaml.org/#3df4eb29
# path        ~/.opam/4.09.0/.opam-switch/build/conf-gnomecanvas.2
# command     ~/.opam/opam-init/hooks/sandbox.sh build pkg-config libgnomecanvas-2.0
# exit-code   1
# env-file    ~/.opam/log/conf-gnomecanvas-2585-b76d46.env
# output-file ~/.opam/log/conf-gnomecanvas-2585-b76d46.out


#=== ERROR while compiling conf-cairo.1 =======================================#
# context     2.0.5 | linux/x86_64 | ocaml-base-compiler.4.09.0 | https://opam.ocaml.org/#3df4eb29
# path        ~/.opam/4.09.0/.opam-switch/build/conf-cairo.1
# command     ~/.opam/opam-init/hooks/sandbox.sh build pkg-config cairo
# exit-code   1
# env-file    ~/.opam/log/conf-cairo-2585-60459a.env
# output-file ~/.opam/log/conf-cairo-2585-60459a.out



<><> Error report <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
┌─ The following actions failed
│ λ build conf-cairo       1
│ λ build conf-gnomecanvas 2
└─ 
╶─ No changes have been performed

[axiomtutor]

It occurred to me to look around for what libgnomecanvas might be. Turns out there's something in my package manager's repositories called libgnomecanvas2-0. So I installed that, ran the OPAM install command, everything worked. I figured I wouldn't delete this issue though, in case it's valuable to you or anyone else to know about the resolution. If I should delete it, let me know.