Fixed error thrown when viewing a channel containing an invalid emoji reaction (#7080)

* Added better error handling for when reacting with a non-existant emoji

* Re-added emoji aliases ca, za, and pk

webapp/components/post_view/reaction/index.js

@@ -23,13 +23,18 @@ function makeMapStateToProps() {
             emoji = ownProps.emojis.get(ownProps.emojiName);
         }
 
+        let emojiImageUrl = '';
+        if (emoji) {
+            emojiImageUrl = getEmojiImageUrl(emoji);
+        }
+
         return {
             ...ownProps,
             profiles,
             otherUsersCount: ownProps.reactions.length - profiles.length,
             currentUserId: getCurrentUserId(state),
             reactionCount: ownProps.reactions.length,
-            emojiImageUrl: getEmojiImageUrl(emoji)
+            emojiImageUrl
         };
     };
 }

webapp/components/post_view/reaction/reaction.jsx

@@ -93,6 +93,10 @@ export default class Reaction extends React.PureComponent {
     }
 
     render() {
+        if (!this.props.emojiImageUrl) {
+            return null;
+        }
+
         let currentUserReacted = false;
         const users = [];
         const otherUsersCount = this.props.otherUsersCount;