Live Reactions should not always expect the comment to be there.

plugin-api/beta/client/hocs/withReaction.js

@@ -54,6 +54,13 @@ export default (reaction) => (WrappedComponent) => {
       id: fragmentId
     });
 
+    if (!data) {
+      if (self) {
+        throw new Error(`Comment ${action.item_id} was not found`);
+      }
+      return;
+    }
+
     // Add our comment from the mutation to the end.
     let idx = data.action_summaries.findIndex(isReaction);
 
@@ -96,6 +103,13 @@ export default (reaction) => (WrappedComponent) => {
       id: fragmentId
     });
 
+    if (!data) {
+      if (self) {
+        throw new Error(`Comment ${action.item_id} was not found`);
+      }
+      return;
+    }
+
     // Check whether we liked this comment.
     const idx = data.action_summaries.findIndex(isReaction);