Book fails to open via OpenBookAsync (Regression)

Description

I have a book that fails to open after updating this library from v3.1.2 to v3.2

My Code:

using var epubBook = EpubReader.OpenBook(filePath, BookReaderOptions);
BookReaderOptions = = new()
    {
        PackageReaderOptions = new PackageReaderOptions()
        {
            IgnoreMissingToc = true
        }
    };

Sample EPUB file

<?xml version="1.0" encoding="utf-8"?>
<package unique-identifier="fanficfare-uid" version="2.0" xmlns="http://www.idpf.org/2007/opf">
    <metadata xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:opf="http://www.idpf.org/2007/opf">
        <dc:identifier id="fanficfare-uid">fanficfare-uid:www.royalroad.com-u87585-s26294</dc:identifier>
        <dc:title id="id">He Who Fights With Monsters</dc:title>
        <dc:creator opf:role="aut">Shirtaloon (Travis Deverell)</dc:creator>
        <dc:contributor id="id-2">FanFicFare [https://github.com/JimmXinu/FanFicFare]</dc:contributor>
        <dc:language>en</dc:language>
        <dc:date opf:event="publication">2019-07-28</dc:date>
        <dc:date opf:event="creation">2022-09-17</dc:date>
        <dc:date opf:event="modification">2022-09-17</dc:date>
        <meta content="2022-09-17T00:00:30" name="calibre:timestamp" />
        <dc:description>Some description here</dc:description>
        <dc:subject>High Fantasy</dc:subject>
        <dc:subject>Last Update: 2022/09/17</dc:subject>
        <dc:subject>LitRPG</dc:subject>
        <dc:subject>Adventure</dc:subject>
        <dc:publisher>www.royalroad.com</dc:publisher>
        <dc:identifier opf:scheme="URL">https://www.royalroad.com/fiction/26294</dc:identifier>
        <dc:source>https://www.royalroad.com/fiction/26294</dc:source>
    </metadata>
    <manifest>
        <item href="toc.ncx" id="ncx" media-type="application/x-dtbncx+xml" />
        <item href="OEBPS/stylesheet.css" id="style" media-type="text/css" />
        <item href="OEBPS/title_page.xhtml" id="title_page" media-type="application/xhtml+xml" />
        <item href="OEBPS/file0001.xhtml" id="file0001" media-type="application/xhtml+xml" />
        ...
        <item href="OEBPS/file0153.xhtml" id="file0153" media-type="application/xhtml+xml" />
    </manifest>
    <spine toc="ncx">
        <itemref idref="title_page" linear="yes" />
        <itemref idref="file0001" linear="yes" />
        ...
        <itemref idref="file0153" linear="yes" />
    </spine>
</package>

I have validated all items exist and table of contents looks fine.

Stack Trace:

[18:47:11 WRN] [BookService] There was an exception when opening epub book: E:\Books\Wont Open\He_Who_Fights_With_Monsters_-_Shirtaloon.epub
System.AggregateException: One or more errors occurred. (Object reference not set to an instance of an object.)
 ---> System.NullReferenceException: Object reference not set to an instance of an object.
   at VersOne.Epub.Internal.BookCoverReader.ReadEpub2CoverFromGuide(EpubSchema epubSchema, Dictionary`2 imageContentRefs)
   at VersOne.Epub.Internal.BookCoverReader.ReadEpub2Cover(EpubSchema epubSchema, Dictionary`2 imageContentRefs)
   at VersOne.Epub.Internal.BookCoverReader.ReadBookCover(EpubSchema epubSchema, Dictionary`2 imageContentRefs)
   at VersOne.Epub.Internal.ContentReader.ParseContentMap(EpubBookRef bookRef, ContentReaderOptions contentReaderOptions)
   at VersOne.Epub.EpubReader.<>c__DisplayClass10_0.<OpenBookAsync>b__1()
   at System.Threading.Tasks.Task`1.InnerInvoke()
   at System.Threading.Tasks.Task.<>c.<.cctor>b__272_0(Object obj)
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
--- End of stack trace from previous location ---
   at VersOne.Epub.EpubReader.OpenBookAsync(IZipFile zipFile, String filePath, EpubReaderOptions epubReaderOptions)
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at System.Threading.Tasks.Task`1.get_Result()
   at VersOne.Epub.EpubReader.OpenBook(String filePath, EpubReaderOptions epubReaderOptions)

[majora2007]

Wow, extremely fast. I’ll take a look and validate and report back to you after work today.

[majora2007]

Okay, then looks like I have enough time. Well, thank you again for the library and especially now that you’re back and improving it. My users have been extremely happy with the recent changes you’ve been making.