[Tilesathome] Sea tiles labelled "unknown type"

[Sebastian Spaeth]

Martin Hawlisch wrote:
> Hi Sebastian,
> 
> now that the redirect to dev is turned off, the lowzoom-stitching for many tiles fail with:
> Can't call method "compare" on an undefined value at ./lowzoom_composite.pl line 150.
> So the server currently deliveres invalid 0 byte png files, which perl GD cannot load, which makes the compare fail.

Thanks for letting me know. I deliver the "unknown" pictures now in the 
cases where we neither have a local file nor know whether its blank land 
or blank sea. Calling such a tile on z=12 level will automatically cause 
a render request, so they should soon go away.

Let me know if you would prefer a transparent tile or whatever rather 
than the "unknown" text.

Sebastian