Error: /undefinedfilename

[PaulRBerg]

After running python dia2pdf.py, I get this:

Working on ./network-fig2.dia
Error: /undefinedfilename in (./network-fig2.dia~)
Operand stack:

Execution stack:
   %interp_exit   .runexec2   --nostringval--   --nostringval--   --nostringval--   2   %stopped_push   --nostringval--   --nostringval--   --nostringval--   false   1   %stopped_push
Dictionary stack:
   --dict:984/1684(ro)(G)--   --dict:0/20(G)--   --dict:78/200(L)--
Current allocation mode is local
Last OS error: No such file or directory
GPL Ghostscript 9.23: Unrecoverable error, exit code 1
You pressed Ctrl+C!

Using macOS 10.13.5 and Python 3.6.5.