A chunk of my gatsby-node.js

file.js

exports.createPages = ({ graphql, actions }) => {
    return new Promise((resolve, reject) => {
        graphql(`
            {
                allMarkdownRemark(
                    sort: { fields: [frontmatter___date], order: DESC }
                ) {
                    edges {
                        node {
                            fields {
                                slug
                            }
                        }
                    }
                }
            }
        `).then(result => {
            if (result.errors) {
                reject(result.errors);
            } else {
                const posts = result.data.allMarkdownRemark.edges;

                // create blog post pages
                posts.forEach(({ node }) => {
                    actions.createPage({
                        path: '/blog/' + node.fields.slug + '/',
                        component: path.resolve('./src/templates/whatever-your-heart-desires.js'),
                        context: {
                            slug: node.fields.slug
                        }
                    });
                });
                
                // more code blah blah blah