singleRender (block, activeBlocks, matches) {
    const selector = `#${block.key}`
    const newVdom = this.renderBlock(null, block, activeBlocks, matches, true)
    const rootDom = document.querySelector(selector)
    const oldVdom = toVNode(rootDom)
    patch(oldVdom, newVdom)
    this.renderMermaid()
    this.renderDiagram()
    this.codeCache.clear()
  }
Only render one block.

@param {object} block
@param {array} activeBlocks
@param {array} matches