No UI shown for invalid command-line options

[focustense]

This led to a very confusing troubleshooting session when someone was trying to run the post-build report on v0.9.3, which didn't support the -z option. Turns out that any problem with the command-line arguments causes the app to start and do literally nothing - no UI, no processing, doesn't even show up in the normal task manager list (have to go to Details).

Ideally the app should simply ignore invalid command-line options and process the valid ones, but failing that, at least show a useful error message instead of going into limbo.