Span with value zero can break application

[adrianbarsi]

Simple counter application:

const patch = init([
    classModule,
    propsModule,
    styleModule,
    eventListenersModule,
])

let currentVnode: VNode = toVNode(document.getElementById('container') as any)

const view = (count: number) => {
   return <div>
       <button on-click={() => render(count+1)}>Increment</button>
       <span>{count}</span>
       <button on-click={() => render(count-1)}>Decrement</button>
   </div>
}

const render = (count: number) => {
    currentVnode = patch(currentVnode, view(count))
}

render(0)

If I increment above the value 0 and then decrement to -1 then it will give me the error: Uncaught TypeError: Node.removeChild: Argument 1 is not an object. It also gives an error if I decrement below 0 and then try to increment to 1. The fix is to change <span>{count}</span to <span>{String(count)}</span>. This behaviour differs from the hyperscript. The following hyperscript has no problems: h("span", null, count). Also the vnode generated shows that the span with a zero has children: {"sel":"span","data":{},"children":[{"text":0}],"text":0} whereas a span with a 1 has: {"sel":"span","data":{},"text":1}