Function checkNodeType

static/katex/katex.js:6025–6035

* Returns the node more strictly typed iff it is of the given type. Otherwise, * returns null.

(node, type)

 */

function checkNodeType(node, type) {
  if (node && node.type === type) {
    // The definition of ParseNode<TYPE> doesn't communicate to flow that
    // `type: TYPE` (as that's not explicitly mentioned anywhere), though that
    // happens to be true for all our value types.
    // $FlowFixMe
    return node;
  }

  return null;
}
/**
 * Asserts that the node is of the given type and returns it with stricter
 * typing. Throws if the node's type does not match.