Re-add newline to error() messages
Re-add newline to error() messages

As reported by @Subo1978, error messages don't have a trailing newline
anymore after commit b77dfdc9. Add back this newline.

dooglus/clams,Kefkius/clams,Jheguy2/Mercury,thunderrabbit/clams,dooglus/clams,nochowderforyou/clams,Kefkius/clams,thunderrabbit/clams,robvanmieghem/clams,dooglus/clams,thunderrabbit/clams,nochowderforyou/clams,dooglus/clams,robvanmieghem/clams,nochowderforyou/clams,robvanmieghem/clams,Kefkius/clams,robvanmieghem/clams,thunderrabbit/clams,nochowderforyou/clams,Jheguy2/Mercury,nochowderforyou/clams,Jheguy2/Mercury,Kefkius/clams,thunderrabbit/clams,Jheguy2/Mercury,Kefkius/clams,dooglus/clams,Jheguy2/Mercury,robvanmieghem/clams