As it stands, if colcon build encounters an error, stretch_create_ament_workspace fails silently (here). This is non-ideal for two reasons:

1. The user thinks it succeeds but it didn't.
2. Once the user realizes that the workspace build didn't succeed, the logical thing they'd try is to manually re-build the workspace. But it is unclear to them that after doing that, they have to re-run stretch_create_ament_workspace because it has to do additional work (e.g., populate URDFs).

(Both these issues arose when the UIUC team was upgrading the workspace on their Stretch 2.)

We should catch when the colcon build fails and provide the user appropriate instructions. If it does not return a failure exit code, we could possible look for all the package names in the install directory, and fail if an expected package does not exist.