fix(dev): Correctly lint scripts typescript files (#4963)

Previously, we've had to tell eslint to ignore TS files in package-level `scripts` directories, because they weren't included by any existing TS eslint config. This fixes that, by adding them to both our main `.eslintrc.js` and (since that new entry needs a tsconfig to which to point) our main `tsconfig.json`.

.eslintrc.js

@@ -33,6 +33,14 @@ module.exports = {
         project: ['tsconfig.test.json'],
       },
     },
+    {
+      files: ['**/scripts/**/*.ts'],
+      parserOptions: {
+        // since filepaths are relative to the working directory, we need to go back up to reach the repo root level
+        // tsconfig
+        project: ['../../tsconfig.json'],
+      },
+    },
     {
       files: ['*.tsx'],
       rules: {

packages/gatsby/.eslintrc.js

@@ -7,6 +7,6 @@ module.exports = {
     jsx: true,
   },
   // ignore these because they're not covered by a `tsconfig`, which makes eslint throw an error
-  ignorePatterns: ['scripts/prepack.ts', 'gatsby-browser.d.ts', 'gatsby-node.d.ts'],
+  ignorePatterns: ['gatsby-browser.d.ts', 'gatsby-node.d.ts'],
   extends: ['../../.eslintrc.js'],
 };

tsconfig.json

@@ -1,6 +1,10 @@
 {
   "extends": "./packages/typescript/tsconfig.json",
 
+  // include scripts here because their TS config isn't package-specific, and they need to be included in a tsconfig
+  // file to be linted
+  "include": ["**/scripts/**/*.ts"],
+
   "compilerOptions": {
     // TODO: turn these on once we switch to only generating types once, using `tsconfig.types.json`
     // "declaration": false,