The asynchronous half of deriveOptions: downloads the style when given its URL, the TileJSON of
every vector source that references one, and the font list of the glyph server the options will use —
osm()'s default, via fetchFontFaces() — and derives the options from all three. Without a font
list, fonts carry over their weight only.
A TileJSON that cannot be downloaded is not fatal — the schema is then recognised from the
source-layers the style reads — and is reported in report.diagnostics. Never throws: an invalid
argument or an unreachable style yields kind: 'unknown' with the reason in the warnings.
The asynchronous half of deriveOptions: downloads the style when given its URL, the TileJSON of every vector source that references one, and the font list of the glyph server the options will use —
osm()'s default, viafetchFontFaces()— and derives the options from all three. Without a font list, fonts carry over their weight only.A TileJSON that cannot be downloaded is not fatal — the schema is then recognised from the source-layers the style reads — and is reported in
report.diagnostics. Never throws: an invalid argument or an unreachable style yieldskind: 'unknown'with the reason in the warnings.