fix: default values, clamp postsPerPage/topicsPerPage to max

src/api/users.js

@@ -109,9 +109,16 @@ usersAPI.updateSettings = async function (caller, data) {
 		throw new Error('[[error:no-privileges]]');
 	}
 
+	let defaults = await user.getSettings(0);
+	defaults = {
+		postsPerPage: defaults.postsPerPage,
+		topicsPerPage: defaults.topicsPerPage,
+		userLang: defaults.userLang,
+		acpLang: defaults.acpLang,
+	};
 	// load raw settings without parsing values to booleans
 	const current = await db.getObject('user:' + data.uid + ':settings');
-	const payload = { ...current, ...data.settings };
+	const payload = { ...defaults, ...current, ...data.settings };
 	delete payload.uid;
 
 	return await user.saveSettings(data.uid, payload);

src/user/settings.js

@@ -47,8 +47,16 @@ module.exports = function (User) {
 		settings.openOutgoingLinksInNewTab = parseInt(getSetting(settings, 'openOutgoingLinksInNewTab', 0), 10) === 1;
 		settings.dailyDigestFreq = getSetting(settings, 'dailyDigestFreq', 'off');
 		settings.usePagination = parseInt(getSetting(settings, 'usePagination', 0), 10) === 1;
-		settings.topicsPerPage = Math.min(settings.topicsPerPage ? parseInt(settings.topicsPerPage, 10) : defaultTopicsPerPage, defaultTopicsPerPage);
-		settings.postsPerPage = Math.min(settings.postsPerPage ? parseInt(settings.postsPerPage, 10) : defaultPostsPerPage, defaultPostsPerPage);
+		settings.topicsPerPage =
+			Math.min(
+				meta.config.maxTopicsPerPage,
+				Math.min(settings.topicsPerPage ? parseInt(settings.topicsPerPage, 10) : defaultTopicsPerPage, defaultTopicsPerPage)
+			);
+		settings.postsPerPage =
+			Math.min(
+				meta.config.maxPostsPerPage,
+				Math.min(settings.postsPerPage ? parseInt(settings.postsPerPage, 10) : defaultPostsPerPage, defaultPostsPerPage)
+			);
 		settings.userLang = settings.userLang || meta.config.defaultLang || 'en-GB';
 		settings.acpLang = settings.acpLang || settings.userLang;
 		settings.topicPostSort = getSetting(settings, 'topicPostSort', 'oldest_to_newest');