.mergeTiles fails for tiny extent

[MichaelChirico]

openmap(c(1.307261, 103.854030), c(1.30536, 103.85531), type = 'mapbox')

Fails with:

Error in .local(x, y, ...) : extents do not overlap

And traceback():

8: stop("extents do not overlap")
7: .local(x, y, ...)
6: crop(rasterImg, ext)
5: crop(rasterImg, ext)
4: raster(x)
3: raster(x)
2: .mergeTiles(map)
1: openmap(c(1.307261, 103.85403), c(1.30536, 103.85531), type = "mapbox")

Poking around a little bit, this appears to be related to auto-zoom maxing out -- maximum zoom level is reached.

I haven't found yet how to tell "how small is too small" of an extent to try and cover... we should be able to code in a stop-gap logic like if (bbox too small) zoom = 18

[MichaelChirico]

Found this:

https://wiki.openstreetmap.org/wiki/Zoom_levels

In any case would be useful to cite this in the docs