`gatsby develop` has started failing

[hrishikesh-k]

Hello.

I was working on customizing the theme before adding my content. However, yesterday, out of nowhere, gatsby develop started returning errors.

"gatsby-plugin-mdx" threw an error while running the onCreateNode lifecycle:

unknown: Support for the experimental syntax 'doExpressions' isn't currently enabled (56:2):

  54 | <h1>{`Let me re-iterate ...`}</h1>
  55 | <p>{`for i in 1 .. 10 `}
> 56 | {do-something(i)}</p>
     |  ^
  57 | <p>{`As you probably guessed, indented 4 spaces. By the way, instead of
  58 | indenting the block, you can use delimited blocks, if you like:`}</p>
  59 | <pre><code  {...{"parentName":"pre"}}>{`define foobar() {

Add @babel/plugin-proposal-do-expressions (https://git.io/vb4S3) to the 'plugins' section of your Babel config to enable transformation.
If you want to leave it as-is, add @babel/plugin-syntax-do-expressions (https://git.io/vb4yh) to the 'plugins' section to enable parsing..../document-site/content/introduction.mdx

I don't know why it's showing 56:2 as the source of error, while, the actual error is caused by content\introduction.mdx at line 39:

    # Let me re-iterate ...
    for i in 1 .. 10 { do-something(i) }

Removing that part, removes the error too, but, code highlighting stops working. First I thought, it was because of something that I changed, but, then, I tried creating another project from scratch and still the same. Can this please be checked?

[hrishikesh-k]

@ChangoMan Sorry to bother you sir, but, it'd be nice to get this theme working as it's not serving any purpose by not working.