Match in diameter_app_SUITE to identify an unexpected path

See this failure in nightly test on one host, indicating that
code:which/1 is returning something other than the expected path:

=== Ended at 2018-06-08 05:10:41
=== Location: [{lists,nth,170},
              {diameter_app_SUITE,app,265},
              {diameter_app_SUITE,'-xref/1-fun-3-',214},
              {lists,'-filter/2-lc$^0/1-0-',1286},
              {diameter_app_SUITE,xref,214},
              {test_server,ts_tc,1545},
              {test_server,run_test_case_eval1,1063},
              {test_server,run_test_case_eval,995}]
=== Reason: no function clause matching lists:nth(2,[]) (lists.erl, line 170)
  in function  diameter_app_SUITE:app/1 (diameter_app_SUITE.erl, line 265)
  in call from diameter_app_SUITE:'-xref/1-fun-3-'/2 (diameter_app_SUITE.erl, line 214)
  in call from lists:'-filter/2-lc$^0/1-0-'/2 (lists.erl, line 1286)
  in call from diameter_app_SUITE:xref/1 (diameter_app_SUITE.erl, line 214)
  in call from test_server:ts_tc/3 (test_server.erl, line 1545)
  in call from test_server:run_test_case_eval1/6 (test_server.erl, line 1063)
  in call from test_server:run_test_case_eval/9 (test_server.erl, line 995)

0 files changed, 0 insertions, 0 deletions