message: Remove unnecessary ! from graphic.finish
diff: @@ -1672,7 +1672,7 @@ export class WindowAreaTool extends ViewTool {
  graphic.setSymbology(color, color, ViewHandleWeight.FatDot);
  graphic.addPointString([this.firstPtWorld]);
  - context.addWorldOverlay(graphic.finish()!);
  + context.addWorldOverlay(graphic.finish());
  return;
  }
  @@ -1695,7 +1695,7 @@ export class WindowAreaTool extends ViewTool {
  this.lineVertPts[1].y = viewRect.bottom;
  gf.addLineString(this.lineVertPts);
  - context.addViewOverlay(gf.finish()!);
  + context.addViewOverlay(gf.finish());
  }
  private computeWindowCorners(): Point3d[] | undefined {
  