gatsby-node.js

const { createFilePath } = require("gatsby-source-filesystem");

// Here we're adding extra stuff to the "node" (like the slug)
// so we can query later for all blogs and get their slug
exports.onCreateNode = ({ node, actions, getNode }) => {
  const { createNodeField } = actions;
  if (node.internal.type === "Mdx") {
    createNodeField({
      // Individual MDX node
      node,
      // Name of the field you are adding
      name: "slug",
      // Generated value
      value: createFilePath({ node, getNode })
    });
  }
};

exports.onCreateWebpackConfig = ({ stage, loaders, actions }) => {
  if (stage === "build-html" || stage === "develop-html") {
    actions.setWebpackConfig({
      module: {
        rules: [
          {
            test: /chartjs-plugin-dragdata/,
            use: loaders.null()
          }
        ]
      }
    });
  }
};