Library not EPUB 3 compatible

[gamebeaker]

If you try to use the Library function with a EPUB 3 it errors out in line 171:

WebToEpub/plugin/js/Library.js

Lines 166 to 172 in e11449b

	if (PreviousEpubTocEpub3Text != null) {
	string1 = "</ol></nav>";
	regex2 = new RegExp(".+<text>");
	regex3 = new RegExp("</text>.+");
	string2 = "<li><a href=\""+ newChaptername.slice(6) + "\">"+AddEpubTocText.match(regex1)[0].replace(regex2, "").replace(regex3, "")+"</a></li>";
	PreviousEpubTocEpub3Text = PreviousEpubTocEpub3Text.replace(string1, string2+string1);
	}

Uncaught (in promise) TypeError: PreviousEpubTocEpub3Text.replace is not a function
PreviousEpubTocEpub3Text should be a string but apparently isn't.