Coerce falsey `className` and `style` values to an empty string to avoid `class="null"` and `style="null"`.
Coerce falsey `className` and `style` values to an empty string to avoid `class="null"` and `style="null"`.

developit/preact,developit/preact,gogoyqj/preact,neeharv/preact,neeharv/preact