prevent infinite loop on topic scroll to bottom

public/src/client/topic.js

@@ -121,7 +121,9 @@ define('forum/topic', [
 		var postIndex = getPostIndex();
 
 		if (postIndex && window.location.search.indexOf('page=') === -1) {
-			navigator.scrollToPost(postIndex - 1, true);
+			if (components.get('post/anchor', postIndex).length) {
+				return navigator.scrollToPostIndex(postIndex - 1, true);
+			}
 		} else if (bookmark && (!config.usePagination || (config.usePagination && pagination.currentPage === 1)) && ajaxify.data.postcount > 1) {
 			app.alert({
 				alert_id: 'bookmark',
@@ -140,10 +142,18 @@ define('forum/topic', [
 
 	function getPostIndex() {
 		var parts = window.location.pathname.split('/');
-		if (parts[parts.length - 1] && utils.isNumber(parts[parts.length - 1])) {
+		var lastPart = parts[parts.length - 1];
-			return parseInt(parts[parts.length - 1], 10);
+		if (lastPart && utils.isNumber(lastPart)) {
+			lastPart = parseInt(lastPart, 10);
+		} else {
+			return 0;
 		}
-		return 0;
+
+		while (lastPart > 0 && !components.get('post/anchor', lastPart).length) {
+			lastPart --;
+		}
+
+		return lastPart;
 	}
 
 	function addBlockQuoteHandler() {

public/src/modules/navigator.js

@@ -175,18 +175,18 @@ define('navigator', ['forum/pagination', 'components'], function(pagination, com
 		navigator.scrollActive = true;
 
 		if (components.get('post/anchor', postIndex).length) {
-			return scrollToPid(postIndex, highlight, duration, offset);
+			return navigator.scrollToPostIndex(postIndex, highlight, duration, offset);
 		}
 
 		if (config.usePagination) {
 			var page = Math.max(1, Math.ceil(postIndex / config.postsPerPage));
 
-			if(parseInt(page, 10) !== pagination.currentPage) {
+			if (parseInt(page, 10) !== pagination.currentPage) {
 				pagination.loadPage(page, function() {
-					scrollToPid(postIndex, highlight, duration, offset);
+					navigator.scrollToPostIndex(postIndex, highlight, duration, offset);
 				});
 			} else {
-				scrollToPid(postIndex, highlight, duration, offset);
+				navigator.scrollToPostIndex(postIndex, highlight, duration, offset);
 			}
 		} else {
 			navigator.scrollActive = false;
@@ -195,14 +195,16 @@ define('navigator', ['forum/pagination', 'components'], function(pagination, com
 		}
 	};
 
-	function scrollToPid(postIndex, highlight, duration, offset) {
+	navigator.scrollToPostIndex = function(postIndex, highlight, duration, offset) {
 		var scrollTo = components.get('post/anchor', postIndex);
 
 		if (!scrollTo.length) {
 			navigator.scrollActive = false;
 			return;
 		}
-
+		offset = offset || 0;
+		duration = duration !== undefined ? duration : 400;
+		navigator.scrollActive = true;
 		var done = false;
 		function animateScroll() {
 			$('html, body').animate({
@@ -232,8 +234,10 @@ define('navigator', ['forum/pagination', 'components'], function(pagination, com
 
 		if (components.get('topic').length) {
 			animateScroll();
+		} else {
+			navigator.scrollActive = false;
 		}
-	}
+	};
 
 
 	return navigator;