OwnComment Page: deleting comment shows failure despite successful

## Change
Due to "Own Comments" being implemented the same way as "Discussion Page", the comment lookup did not work for the abandoning case.

Just skip the local cleanup of `byId` -- it doesn't matter, as the GUI uses `selectCommentsForUri` to grab the per-channel comments, so it would still disappear in the GUI immediately.

ui/redux/reducers/comments.js

@@ -575,6 +575,8 @@ export default handleActions(
 
       // to remove the comment and its references
       const claimId = comment.claim_id;
+
+      if (byId[claimId]) {
         for (let i = 0; i < byId[claimId].length; i++) {
           if (byId[claimId][i] === comment_id) {
             // immutable update
@@ -583,6 +585,7 @@ export default handleActions(
             break;
           }
         }
+      }
 
       // Update replies
       if (comment['parent_id'] && repliesByParentId[comment.parent_id]) {