Move lint task calls to watch task

Helps reduce duplication in `gulpfile.mjs` once we start to move directory and file path configs over

gulpfile.mjs

@@ -15,10 +15,7 @@ import { npmScriptTask } from './tasks/run.mjs'
  * Runs JavaScript code quality checks, documentation, compilation
  */
 gulp.task('scripts', gulp.series(
-  gulp.parallel(
-    npmScriptTask('lint:js'),
-    compileJavaScripts
-  ),
+  compileJavaScripts,
   npmScriptTask('build:jsdoc')
 ))
 
@@ -27,10 +24,7 @@ gulp.task('scripts', gulp.series(
  * Runs Sass code quality checks, documentation, compilation
  */
 gulp.task('styles', gulp.series(
-  gulp.parallel(
-    npmScriptTask('lint:scss'),
-    compileStylesheets
-  ),
+  compileStylesheets,
   npmScriptTask('build:sassdoc')
 ))
 
@@ -41,10 +35,8 @@ gulp.task('styles', gulp.series(
 gulp.task('build:public', gulp.series(
   clean,
   copyAssets,
-  compileJavaScripts,
-  compileStylesheets,
-  npmScriptTask('build:jsdoc'),
-  npmScriptTask('build:sassdoc')
+  'scripts',
+  'styles'
 ))
 
 /**

tasks/gulp/watch.mjs

@@ -2,12 +2,13 @@ import gulp from 'gulp'
 import slash from 'slash'
 
 import { paths } from '../../config/index.js'
+import { npmScriptTask } from '../run.mjs'
 
 /**
  * Watch task
  * During development, this task will:
- * - run `gulp styles` when `.scss` files change
- * - run `gulp scripts` when `.mjs` files change
+ * - lint and run `gulp styles` when `.scss` files change
+ * - lint and run `gulp scripts` when `.mjs` files change
  *
  * @returns {Promise<import('fs').FSWatcher[]>} Array from file system watcher objects
  */
@@ -18,12 +19,18 @@ export function watch () {
       `${slash(paths.app)}/**/*.scss`,
       `${slash(paths.src)}/govuk/**/*.scss`,
       `!${slash(paths.src)}/govuk/vendor/*`
-    ], gulp.series('styles')),
+    ], gulp.parallel(
+      npmScriptTask('lint:scss'),
+      'styles'
+    )),
 
     gulp.watch([
       'jsdoc.config.js',
       `${slash(paths.src)}/govuk/**/*.mjs`
-    ], gulp.series('scripts'))
+    ], gulp.parallel(
+      npmScriptTask('lint:js'),
+      'scripts'
+    ))
   ])
 }