Filters the list of file types allowed for editing in the plugin file editor.
Parameters
$default_typesstring[]- An array of editable plugin file extensions.
$pluginstring- Path to the plugin file relative to the plugins directory.
Source
$file_types = (array) apply_filters( 'editable_extensions', $default_types, $plugin );
On the theme file editor, use the wp_theme_editor_filetypes hook to filter the file extensions.