fix(gatsby-plugin-mdx): pass the correct options to setParserP… (#18243)

* pass correct options to setParserPlugins

* ensure plugin.options is not undefined

Co-Authored-By: Michal Piechowiak <[email protected]>

* chore: format

Author: d4rekanguok

packages/gatsby-plugin-mdx/gatsby/source-nodes.js

@@ -90,7 +90,7 @@ module.exports = (
     debug(`required`, plugin)
     if (_.isFunction(requiredPlugin.setParserPlugins)) {
       for (let parserPlugin of requiredPlugin.setParserPlugins(
-        plugin.pluginOptions
+        plugin.options || {}
       )) {
         if (_.isArray(parserPlugin)) {
           const [parser, parserPluginOptions] = parserPlugin