muted_topics: Rerender list only if modal is opened and section is loaded.

We should rernder the muted topics list in settings only if the settings
modal is opened and the muted topics section is loaded.

frontend_tests/node_tests/settings_muting.js

@@ -32,7 +32,10 @@ run_test('settings', () => {
         set_up_ui_called = true;
     };
 
+    assert.equal(settings_muting.loaded, false);
+
     settings_muting.set_up();
+    assert.equal(settings_muting.loaded, true);
 
     const click_handler = $('body').get_on_handler('click', '.settings-unmute-topic');
     assert.equal(typeof click_handler, 'function');
@@ -71,3 +74,8 @@ run_test('settings', () => {
     assert(set_up_ui_called);
     assert.equal(data_called, 2);
 });
+
+run_test('reset', () => {
+    settings_muting.reset();
+    assert.equal(settings_muting.loaded, false);
+});

static/js/muting_ui.js

@@ -20,7 +20,9 @@ exports.rerender = function () {
     if (current_msg_list !== home_msg_list) {
         home_msg_list.update_muting_and_rerender();
     }
-    exports.set_up_muted_topics_ui();
+    if (overlays.settings_open() && settings_muting.loaded) {
+        exports.set_up_muted_topics_ui();
+    }
 };
 
 exports.persist_mute = function (stream_id, topic_name) {

static/js/settings_muting.js

@@ -1,4 +1,7 @@
+exports.loaded = false;
+
 exports.set_up = function () {
+    exports.loaded = true;
     $('body').on('click', '.settings-unmute-topic', function (e) {
         const $row = $(this).closest("tr");
         const stream_id = parseInt($row.attr("data-stream-id"), 10);
@@ -13,4 +16,8 @@ exports.set_up = function () {
     muting_ui.set_up_muted_topics_ui();
 };
 
+exports.reset = function () {
+    exports.loaded = false;
+};
+
 window.settings_muting = exports;

static/js/settings_sections.js

@@ -77,6 +77,7 @@ exports.reset_sections = function () {
     settings_profile_fields.reset();
     settings_streams.reset();
     settings_user_groups.reset();
+    settings_muting.reset();
     // settings_users doesn't need a reset()
 };