message: update spell for moved pg markers to after pg
diff: @@ -122,6 +122,9 @@ class Speller {
  delta.type === mergeTree.MergeTreeDeltaType.REMOVE) {
  let pgMarker = this.sharedString.client.mergeTree.findTile(delta.pos1,
  this.sharedString.client.getClientId(), "pg");
  + if (!pgMarker) {
  + pgMarker = { tile: undefined, pos: 0};
  + }
  this.pendingParagraphs.push(pgMarker);
  } else if (delta.type === mergeTree.MergeTreeDeltaType.GROUP) {
  for (let groupOp of delta.ops) {
  @@ -159,8 +162,11 @@ class Speller {
  }
  if (this.pendingParagraphs.length > 0) {
  for (let pg of this.pendingParagraphs) {
  - const offset = this.sharedString.client.mergeTree.getOffset(pg.tile, mergeTree.UniversalSequenceNumber,
  + let offset = 0;
  + if (pg.tile) {
  + offset = this.sharedString.client.mergeTree.getOffset(pg.tile, mergeTree.UniversalSequenceNumber,
  this.sharedString.client.getClientId());
  + }
  const endMarkerPos = this.sharedString.client.mergeTree.findTile(offset,
  this.sharedString.client.getClientId(), "pg", false);
  let endPos: number;
  