fix: verify if document exists

[gabrielzevedo]

Fix this error: #181

[glromeo]

I don't think your fix makes sense...have you actually tested it?
The point in which you check for document to be defined is within
the esbuild process...that's not where you want to do it
If anything one should provide a lazy load implementation that hydrates
the style module but I don't fully understand if this is a SSR issue and
I don't have anyway the capacity to ensure SSR coverage therefore I am inclined not
to change style modules for the moment