Fix KeyError crash on OSX if using different terminal

[davetcoleman]

Silently fail to create notification instead of crashing. Using get will return None if a key is not present rather than raise a KeyError

Background: I'm working on OSX via a SSH shell in Linux (can't stand those key bindings :) ) and I don't have the TERM_PROGRAM env variable. All I have is TERM, which is valued as TERM=xterm

[NikolausDemmel]

Hang on, so your Host is Linux and you ssh into OSX? (I initially understood it the other way round, mazbe because I'm biased towards liking the OSX keybindings :-P)

Your change will still (try to) invoke the notification, just without the "activation" of the terminal app. I take it that results in neither a notification, nor an error in your scenario?

[davetcoleman]

lol, yes, I prefer linux.

I still get a notification on the host OSX, but of course not on the SSH terminal I'm working from in Linux

This PR fixes a bug, and doesn't add any new features/functionality

[NikolausDemmel]

Ah ok, I just wanted to check if the notification itself causes any issues in the SSH scenario.

So +1 from me.

Maybe a source code comment would be nice to point out that "TERM_PROGRAM does not exists" is really a valid use case here. Maybe something like:

# try to use the environment to detect the use of a known terminal program and bring it
# to the foreground in addition to the desktop notification

[wjwwood]

lol, yes, I prefer linux.

Are you talking about copy, paste, etc hotkeys? How weird 😄, I always found OS X's hot keys to make more sense.

The fix looks ok to me, I'll probably add an explicit default argument in a follow up commit (I don't care for the readability of the implicit None default that .get() has).

[davetcoleman]

I've trained myself for years to be really good at emac's Alt/Ctrl shortcut keys and all that goes away on a Mac keyboard. I've never fully figured out alt key bindings on a mac