Changed mention parser to ignore empty string mentions

webapp/utils/text_formatting.jsx

@@ -213,6 +213,11 @@ function highlightCurrentMentions(text, tokens) {
     }
 
     for (const mention of UserStore.getCurrentMentionKeys()) {
+        // occasionally we get an empty mention which matches a bunch of empty strings
+        if (!mention) {
+            continue;
+        }
+
         output = output.replace(new RegExp(`(^|\\W)(${escapeRegex(mention)})\\b`, 'gi'), replaceCurrentMentionWithToken);
     }