Same bug here, i don’t understand why.
In lib.php (included in functions.php), i have:
add_action('after_setup_theme', function () {
...
add_editor_style(get_template_directory_uri('dist/editor.styles.css'));
...
}, 20);
it is supposed to load httpdocs/app/themes/wp-starter2017/dist/editor.styles.css
the editor.styles.css is built with webpack2 and contains at the moment only:
body{background-color:#f39}
/*# sourceMappingURL=editor.styles.css.map*/
No @import or whatever else.
In the network tab, i have HTTP 500 error on the file https://wp-starter2.test/app/themes/wp-starter2017/?wp-mce-4603-20170530, if i comment add_editor_style, this error disappears.
