Peast\Syntax\Exception: Unexpected: async in Peast\Syntax\ParserAbstract->error() (line 305 of D:\xampp\htdocs\thinkindrupal1\vendor\mck89\peast\lib\Peast\Syntax\ParserAbstract.php

Problem/Motivation

It seems that Drupal core does not support async very well. get error :
Peast\Syntax\Exception: Unexpected: async in Peast\Syntax\ParserAbstract->error() (line 305 of D:\xampp\htdocs\thinkindrupal1\vendor\mck89\peast\lib\Peast\Syntax\ParserAbstract.php).

not preprocess js works. when preprocess js, get this error.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes