message: only add to pending list if the op is submitted
diff: @@ -356,8 +356,9 @@ export class SharedString extends CollaborativeMap {
  ops: opList,
  type: MergeTree.MergeTreeDeltaType.GROUP,
  } as MergeTree.IMergeTreeGroupMsg;
  - this.client.mergeTree.pendingSegments.enqueue(segmentGroup);
  +
  if (groupOp.ops.length > 0) {
  + this.client.mergeTree.pendingSegments.enqueue(segmentGroup);
  this.submitIfAttached(groupOp);
  }
  }
  