Check for not blank strings instead of not empty

[freya022]

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Closes Issue: NaN

Description

So users can't pass blank IDs/URLs/labels as valid ones.

[MineKing9534]

Passing blank strings for button labels seems to be allowed. I tried passing ZERO_WIDTH_SPACE as button label and it works perfectly fine

[freya022]

Whats the point of having a ZWSP as the label

[MineKing9534]

Whats the point of having a ZWSP as the label

I don't know a specific use case but it is possible so I don't see a reason to prevent it