[core, android] Factor JSON string conversions

This adds a `convertJSON` template, to be used like:

   Error error
   optional<Foo> foo = convertJSON<Foo>(string, error);

Internally, it parses the string with RapidJSON and then calls `convert<Foo>(parsed, error)`.

While here, rationalize GeoJSON converters and fix error handling for Tileset conversion in OfflineDownload.

1 files changed, 1 insertions, 1 deletions

diff --git a/include/mbgl/style/conversion/source.hpp b/include/mbgl/style/conversion/source.hpp
index 2371183b1c..dc7cdc0d42 100644
--- a/include/mbgl/style/conversion/source.hpp
+++ b/include/mbgl/style/conversion/source.hpp
@@ -122,7 +122,7 @@ private:
         auto result = std::make_unique<GeoJSONSource>(id, *options);
 
         if (isObject(*dataValue)) {
-            optional<GeoJSON> geoJSON = convertGeoJSON(*dataValue, error);
+            optional<GeoJSON> geoJSON = convert<GeoJSON>(*dataValue, error);
             if (!geoJSON) {
                 return {};
             }