ESRI: how to handle 'blank tile' behaviour

[pietervdvn]

The ESRI-layers (esp EsriWorldImagery) don't have tiles on some locations for high zoom levels.
ESRI handles this by inserting a 'blank tile' (which is a gray jpg/png with the text 'no imagery available here')

However, when adding ?blankTile=false to the URL, it gives a '404' instead of a blank tile, which many mapping libraries (leaflet & maplibre) interpret as "let us use the higher zoom level and overzoom that", which is more useful.

The question now is: how should we deal with this in the ELI? IMHO, this behaviour should at least be documented in the "description"-fields of those layers, but we might even opt to add the parameter by default

[simonpoole]

This already handled with the no_tile_header field https://github.com/osmlab/editor-layer-index/blob/gh-pages/sources%2Fworld%2FEsriImagery.geojson that is set by ESRI when there is no tile.