在0.10.3版本中，如果对方是 shtml 页面，则会直接报错

In version 0.10.3, if the other party is an shtml page, the error is as follows: process request Request{url='https://www.prlife.com.cn/page/message/base/product/list/product_help_list.shtml', method='null', extras=null, priority=0, headers={}, cookies={}} error java.lang.NullPointerException: null at java.util.regex.Matcher.getTextLength(Matcher.java:1283) at java.util.regex.Matcher.reset(Matcher.java:309) at java.util.regex.Matcher.<init>(Matcher.java:229) at java.util.regex.Pattern.matcher(Pattern.java:1093) at us.codecraft.webmagic.utils.UrlUtils.getCharset(UrlUtils.java:119) at us.codecraft.webmagic.utils.CharsetUtils.detectCharset(CharsetUtils.java:28) at us.codecraft.webmagic.downloader.HttpClientDownloader.getHtmlCharset(HttpClientDownloader.java:128) at us.codecraft.webmagic.downloader.HttpClientDownloader.handleResponse(HttpClientDownloader.java:112) at us.codecraft.webmagic.downloader.HttpClientDownloader.download(HttpClientDownloader.java:82) at us.codecraft.webmagic.Spider.processRequest(Spider.java:445) at us.codecraft.webmagic.Spider.access$000(Spider.java:65) at us.codecraft.webmagic.Spider$1.run(Spider.java:349) at us.codecraft.webmagic.thread.CountableThreadPool$1.run(CountableThreadPool.java:74) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at java.lang.Thread.run(Thread.java:748)