fix NoneType is not interable in case of no port mapping

[chassing]

in case a service doesn't use a port mapping (see compose.yml server db) port_mappings_from_container failed with "NoneType is not interable". container addresses is None instead of an empty list.

compose.yml:

version: '2'
services:
db:
image: postgres
web:
image: brogency/hello-world
ports:
- "8000"
depends_on:
- db

[ShaneDrury]

@chassing Looks good and the fix works! Thank you.
Do you mind if I make a small formatting change to port_mappings_from_container and add a test for the behaviour you describe?
I can release a new version of this afterwards.

[ShaneDrury]

Actually, I can't push to your branch, so I'll merge this in and then merge the test/formatting fix.

[ShaneDrury]

👍

[ShaneDrury]

Released in https://github.com/ShaneDrury/dockerintegration/releases/tag/0.0.2