[Elm] Fix printing empty notes

[Qluxzz]

Fix printing empty notes since an empty string is truthy

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  @eriktim

[Qluxzz]

I know there's an option to change this globally for the entire code generator but I feel like doing this explicitly and keeping the standard compiler behavior of treating empty strings as true might be good.

[wing328]

Right. I'm ok with your approach. Let's give it a try.