Return NODE_NAME_NON_EXISTENT instead of ERROR.

[evshary]

There are some return value errors in CI test of rcl and rclaction, like this.

I think we should have the return value RMW_RET_NODE_NAME_NON_EXISTENT if we can't get the node.

Signed-off-by: evshary evshary@gmail.com

[eboasson]

I agree — see also ros2/rmw#182, ros2/rmw_opensplice#281 and ros2/rmw_fastrtps#311.

[dirk-thomas]

I would expect you to need separate branches for this. The master branch will work with the master branches of ROS 2 but e.g. for Dashin this won't work since this new error code isn't available in Dashing (and I would expect it not being backported).

[eboasson]

Oops. Thanks for warning me, @dirk-thomas. Clearly I'm not quite used to tracking moving targets yet — which is quite strange for someone who once worked for a radar company.

Methinks #45 should solve it.