If a plugin returns no output, don't update the menu.

[matryer]

...However, it seems if the script produces no output it wipes out the menu portion which defeats my purpose. If you could somehow build a fix such that if the script sends no output that nothing is changed in the current display that would be great...

Originally posted by @mlcampbe in #738 (comment)

[matryer]

@leaanthony Can you think of any reason not to do this? I doubt people are relying on this behaviour to have an empty plugin with empty space, are they?

[leaanthony]

Seems like a legit use case. Should be a case of checking the output and only calling update if it's not blank