Hi Roman König sorry for the confusion on this. You are right that normal usage of TileLayers should not be flooding the console with errors. However, one problem with requesting blankTiles is that if a user starts zoomed in, then you might run into a situation where no data is displayed despite there being data in a parent tile. We will be fixing the logic to properly request parent tiles when data for a tile at a given LOD is missing, and also avoid flooding the console with these errors.
We're making an internal issue (#22922) to track this, not sure that this will make it in 4.13, but we can definitely address for 4.14.