fix(txt): more robust txt parsing, closes #3970 (#3983)

apps/readest-app/src/utils/book.ts

@@ -317,6 +317,7 @@ export interface MetadataHashInfo {
 }
 
 export const getMetadataHashInfo = (metadata: BookMetadata): MetadataHashInfo | undefined => {
+  if (!metadata) return;
   try {
     const title = getTitleForHash(metadata.title);
     const authors = getAuthorsList(metadata.author);

apps/readest-app/src/utils/txt.ts

@@ -634,8 +634,8 @@ export class TxtToEpubConverter {
           String.raw`(?:^|\n)\s*` +
             '(' +
             [
-              String.raw`第[ 　零〇一二三四五六七八九十0-9][ 　零〇一二三四五六七八九十百千万0-9]*(?:[章卷节回讲篇封本册部话])(?:[：:、 　\(\)0-9]*[^\n-]{0,24})(?!\S)`,
-              String.raw`(?:楔子|前言|简介|引言|序言|序章|总论|概论|后记)(?:[：: 　][^\n-]{0,24})?(?!\S)`,
+              String.raw`第[ 　零〇一二三四五六七八九十0-9][ 　零〇一二三四五六七八九十百千万0-9]*(?:[章卷节回讲篇封本册部话])(?:[：:、 　\(\)0-9]*[^\n-]{0,36})(?!\S)`,
+              String.raw`(?:楔子|前言|简介|引言|序言|序章|总论|概论|后记)(?:[：: 　][^\n-]{0,36})?(?!\S)`,
               String.raw`chapter[\s.]*[0-9]+(?:[：:. 　]+[^\n-]{0,50})?(?!\S)`,
             ].join('|') +
             ')',
@@ -647,7 +647,7 @@ export class TxtToEpubConverter {
           String.raw`(?:^|\n)\s*` +
             '(' +
             [
-              String.raw`[一二三四五六七八九十][零〇一二三四五六七八九十百千万]?[：:、 　][^\n-]{0,24}(?=\n|$)`,
+              String.raw`[一二三四五六七八九十][零〇一二三四五六七八九十百千万]?[：:、 　][^\n-]{0,36}(?=\n|$)`,
               String.raw`[0-9]+[^\n]{0,16}(?=\n|$)`,
             ].join('|') +
             ')',