Handle errors

[rgabo]

• Check whether exec calls are successful or error out
• Log error and bail if exec fails
• Clean up after running docker-ssh locally using run-dev.sh

[rgabo]

@jeroenpeeters let me know if the cleanup makes sense to you. Also, please comment on the code if you have any feedback or questions.

I wonder what dependency caused the failure exactly, but I was not able to investigate that yet.