@evilebottnawi @ikatyang I have no idea why babel parser throws, and loc is undefined only on Node 4, would you like to help?

Besides, the error come from

You could try changing that section to this:

if (error.loc) {
  throw createError(
    // babel error prints (l:c) with cols that are zero indexed
    // so we need our custom error
    error.message.replace(/ \(.*\)/, ""),
    {
      start: {
        line: error.loc.line,
        column: error.loc.column + 1
      }
    }
  );
} else {
  throw error;
}

That should show you the real error that’s causing the crash.

It seems Array#includes is not polyfilled on Node 4.

@j-f1 The tests have been fixed, would you like to review again?

@evilebottnawi @ikatyang Please help to review.

Sorry, i am not familiar with mdx, i can't review

I'm not really familiar with MDX too albeit I learnt a lot about it today. =)

@evilebottnawi @ikatyang @thorn0

This PR becomes much cleaner and easier for reviewing after #6949 been merged, thanks for @thorn0's great work.

Please help to review it.