[ExHentai] Fix pagination

src/main/kotlin/org/koitharu/kotatsu/parsers/site/ExHentaiParser.kt

@@ -105,7 +105,7 @@ internal class ExHentaiParser(
 				return getListPage(page, query, tags, sortOrder)
 			}
 		updateDm = false
-		nextPages[page + 1] = getNextTimestamp(root)
+		nextPages[page + 1] = getNextTimestamp(body)
 		return root.children().mapNotNull { tr ->
 			if (tr.childrenSize() != 2) return@mapNotNull null
 			val (td1, td2) = tr.children()

src/test/kotlin/org/koitharu/kotatsu/parsers/MangaParserTest.kt

@@ -36,6 +36,8 @@ internal class MangaParserTest {
 		val parser = source.newParser(context)
 		val page1 = parser.getList(0, sortOrder = null, tags = null)
 		val page2 = parser.getList(page1.size, sortOrder = null, tags = null)
+		assert(page1.isNotEmpty()) { "Page 1 is empty" }
+		assert(page2.isNotEmpty()) { "Page 2 is empty" }
 		val intersection = page1.intersect(page2.toSet())
 		assert(intersection.isEmpty()) {
 			"Pages are intersected by " + intersection.size