ERROR #85923 GRAPHQL - Cannot query field

[kbs-code]

Description

My goal is that the markdown document be rendered as children alongside the layout.
When I attempt to run "gatsby develop" in the top level directory of my project, I get several errors. Here is one:

 ERROR #85923  GRAPHQL

There was an error in your GraphQL query:

Cannot query field "slug" on type "MarkdownRemarkFrontmatter".

If you don't expect "slug" to exist on the type "MarkdownRemarkFrontmatter" it is most likely
 a typo.
However, if you expect "slug" to exist there are a couple of solutions to common problems:

- If you added a new data source and/or changed something inside
gatsby-node.js/gatsby-config.js, please try a restart of your development server
- The field might be accessible in another subfield, please try your query in GraphiQL and
use the GraphiQL explorer to see which fields you can query and what shape they have
- You want to optionally use your field "slug" and right now it is not used anywhere.
Therefore Gatsby can't infer the type and add it to the GraphQL schema. A quick fix is to add
 at least one entry with that field ("dummy content")

It is recommended to explicitly type your GraphQL schema if you want to use optional fields.
This way you don't have to add the mentioned "dummy content". Visit our docs to learn how you
 can define the schema for "MarkdownRemarkFrontmatter":
https://www.gatsbyjs.com/docs/reference/graphql-data-layer/schema-customization#creating-type
-definitions

File: src/pages/{MarkdownRemark.frontmatter__slug}.js:29:9

Steps to reproduce

Minimal reproduction: https://github.com/kirillmcclintock/gatsby-bug-repro

Clone the github repo. Run "gatsby develop". Observe errors.

Expected result

The "gatsby develop" command should finish without errors.

Actual result

The "gatsby develop" command returns errors.

  System:
    OS: Linux 4.19 Debian GNU/Linux 10 (buster) 10 (buster)
    CPU: (8) x64 Intel(R) Xeon(R) CPU E3-1505M v5 @ 2.80GHz
    Shell: 5.7.1 - /bin/zsh
  Binaries:
    Node: 14.17.0 - ~/bin/nodejs/bin/node
    npm: 7.17.0 - ~/bin/nodejs/bin/npm
  Languages:
    Python: 2.7.16 - /usr/bin/python
  Browsers:
    Chrome: 91.0.4472.114
    Firefox: 89.0.1
  npmPackages:
    gatsby: ^3.6.2 => 3.6.2
    gatsby-source-filesystem: ^3.8.0 => 3.8.0
    gatsby-transformer-remark: ^4.5.0 => 4.5.0
  npmGlobalPackages:
    gatsby-cli: 3.8.0

[kbs-code]

The issue was the extra blank line above the first set of dashes in some-markdown.md. Deleting it solved the problem.