Avoid inserting invalid dates and/or empty divs

src/converse-chatview.js

@@ -536,6 +536,9 @@ converse.plugins.add('converse-chatview', {
                       prev_msg_date = _.isNull(prev_msg_el) ? null : prev_msg_el.getAttribute('data-isodate'),
                       next_msg_date = next_msg_el.getAttribute('data-isodate');
 
+                if (_.isNull(prev_msg_date) && _.isNull(next_msg_date)) {
+                    return;
+                }
                 if (_.isNull(prev_msg_date) || moment(next_msg_date).isAfter(prev_msg_date, 'day')) {
                     const day_date = moment(next_msg_date).startOf('day');
                     next_msg_el.insertAdjacentHTML('beforeBegin',
@@ -725,7 +728,10 @@ converse.plugins.add('converse-chatview', {
                  */
                 const view = new _converse.MessageView({'model': message});
                 await view.render();
-                
+
+                if (!view.el.innerHTML) {
+                    return _converse.log("showMessage: message's view element is empty", Strophe.LogLevel.ERROR);
+                }
                 this.clearChatStateNotification(message);
                 this.insertMessage(view);
                 this.insertDayIndicator(view.el);