fix: add info message if gatsby-config.js could have been typo'd

packages/gatsby/package.json

@@ -42,6 +42,7 @@
     "express": "^4.14.0",
     "express-graphql": "^0.6.6",
     "extract-text-webpack-plugin": "^1.0.1",
+    "fast-levenshtein": "~2.0.4",
     "file-loader": "^0.9.0",
     "flat": "^2.0.1",
     "friendly-errors-webpack-plugin": "^1.6.1",

packages/gatsby/src/bootstrap/get-config-file.js

@@ -0,0 +1,35 @@
+/* @flow */
+const levenshtein = require('fast-levenshtein');
+const fs = require('fs-extra');
+const testRequireError = require(`../utils/test-require-error`);
+const report = require(`gatsby-cli/lib/reporter`);
+const chalk = require('chalk');
+
+function isNearMatch(fileName: string, configName: string, distance: number): boolean {
+  return levenshtein.get(fileName, configName) <= distance;
+}
+
+module.exports = async function getConfigFile(rootDir: string, configName: string, distance: number = 3) {
+  const configPath = `${rootDir}/${configName}`;
+  try {
+    return require(configPath);
+  } catch (err) {
+    const nearMatch = await fs.readdir(rootDir)
+      .then(files => {
+        return files
+          .find(file => {
+            const fileName = file.split(rootDir).pop();
+            return isNearMatch(fileName, configName, distance);
+          });
+      });
+    if (!testRequireError(configPath, err)) {
+      report.error(`Could not load ${configName}`, err);
+      process.exit(1);
+    } else if (nearMatch) {
+      console.log('');
+      report.error(`It looks like you were trying to add the config file? Please rename "${chalk.bold(nearMatch)}" to "${chalk.bold(configName)}"`);
+      console.log('');
+      process.exit(1);
+    }
+  }
+};

packages/gatsby/src/bootstrap/index.js

@@ -16,6 +16,7 @@ const { store, emitter } = require(`../redux`)
 const loadPlugins = require(`./load-plugins`)
 const { initCache } = require(`../utils/cache`)
 const report = require(`gatsby-cli/lib/reporter`)
+const getConfigFile = require('./get-config-file');
 
 // Show stack trace on unhandled promises.
 process.on(`unhandledRejection`, (reason, p) => {
@@ -72,16 +73,7 @@ module.exports = async (args: BootstrapArgs) => {
   // Try opening the site's gatsby-config.js file.
   activity = report.activityTimer(`open and validate gatsby-config.js`)
   activity.start()
-  let config
-  try {
-    // $FlowFixMe
-    config = preferDefault(require(`${program.directory}/gatsby-config`))
-  } catch (err) {
-    if (!testRequireError(`${program.directory}/gatsby-config`, err)) {
-      report.error(`Could not load gatsby-config`, err)
-      process.exit(1)
-    }
-  }
+  const config = await preferDefault(getConfigFile(program.directory, 'gatsby-config.js'));
 
   store.dispatch({
     type: `SET_SITE_CONFIG`,