Any ideas what might be sparking? 

This is a new mint 19 system.  The test below is the opam install output and a psql test.  I also tried installing a pinned version from the github repo with the same error.

  

=-=- Gathering sources =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

[postgresql] Archive in cache

=-=- Processing actions -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

[ERROR] The compilation of postgresql failed at "jbuilder build -p postgresql -j 4".

#=== ERROR while installing postgresql.4.4.0 ==================================#

# opam-version 1.2.2

# os           linux

# command      jbuilder build -p postgresql -j 4

# path         /home/caseybasichis/.opam/4.07.0/build/postgresql.4.4.0

# compiler     4.07.0

# exit-code    1

# env-file     /home/caseybasichis/.opam/4.07.0/build/postgresql.4.4.0/postgresql-16795-5f1023.env

# stdout-file  /home/caseybasichis/.opam/4.07.0/build/postgresql.4.4.0/postgresql-16795-5f1023.out

# stderr-file  /home/caseybasichis/.opam/4.07.0/build/postgresql.4.4.0/postgresql-16795-5f1023.err

### stderr ###

# -> stdout:

# [...]

#  | cmxa_magic_number: Caml1999Z023

#  | ast_impl_magic_number: Caml1999M023

#  | ast_intf_magic_number: Caml1999N023

#  | cmxs_magic_number: Caml1999D023

#  | cmt_magic_number: Caml1999T023

# -> stderr:

# Fatal error: exception End_of_file

# Raised at file "src/configurator.ml", line 511, characters 13-22

# Called from file "src/config/discover.ml", line 6, characters 2-1023

=-=- Error report -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

The following actions failed

  ∗  install postgresql 4.4.0

No changes have been performed

=-=- postgresql.4.4.0 troobleshooting -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

=> This package relies on external (system) dependencies that may be missing. `opam depext postgresql.4.4.0' may help

   you find the correct installation for your system.