Paths section should not be required

[nsheff]

Related to #285

Should the new paths section be required?

Traceback (most recent call last):
  File "/home/ns5bc/.local/bin/looper", line 10, in <module>
    sys.exit(main())
  File "/home/ns5bc/.local/lib/python3.6/site-packages/looper/looper.py", line 743, in main
    run(args, rerun=(args.command == "rerun"), **compute_kwargs)
  File "/home/ns5bc/.local/lib/python3.6/site-packages/looper/looper.py", line 351, in __call__
    curr_pl_fails = cndtr.add_sample(sample, rerun=rerun)
  File "/home/ns5bc/.local/lib/python3.6/site-packages/looper/conductor.py", line 294, in add_sample
    self.submit()
  File "/home/ns5bc/.local/lib/python3.6/site-packages/looper/conductor.py", line 352, in submit
    script = self.write_script(self._pool, self._curr_size)
  File "/home/ns5bc/.local/lib/python3.6/site-packages/looper/conductor.py", line 526, in write_script
    self.pl_iface.render_paths(namespaces=namespaces)
  File "/home/ns5bc/.local/lib/python3.6/site-packages/looper/pipeline_interface.py", line 75, in render_paths
    raise AttributeError(f"'{PATHS_KEY}' section not found in the "
AttributeError: 'paths' section not found in the PipelineInterface object.

[nsheff]

I tried to put in paths: null and got:

Ignoring invalid pipeline interface source: /sfs/qumulo/qproject/shefflab/deploy/plantref/plantref/pipeline_interfaces/wget_piface.
yaml. Caught exception: None is not of type 'object'

[nsheff]

it works if I do:

paths:
  dummy: dummy

So I think the paths should not be required.

[stolarczyk]

Ah ok I forgot that the command_template can just specify a command that's not necessarily sourced from paths.

[nsheff]

yeah, like refgenie build