fix(test): exit test command if karma finishes execution

[edusperoni]

PR Checklist

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What is the current behavior?

the test command does not exit when karma exits with error code 0

What is the new behavior?

cli exits with code 0 when karma finishes it's execution

Fixes #5617.

[edusperoni]

@rigor789 can this be merged? From my tests, any error code != 0 will throw already, so this line is only reached when karma hasn't errored out

[rigor789]

Sure, just haven't been working on the CLI recently - but I'll merge it and it should get auto-published to @next