[core] Don't use exceptions in MapObserver::onDidFailLoadingMap

Using different exception pointers to specify the loading failure makes
an awkward API. Most users rethrow the exception only to figure out what
type of error happened so it can be reported properly. So replace the
exception pointer with a enum an string description of the failure.

1 files changed, 8 insertions, 2 deletions

diff --git a/include/mbgl/map/map_observer.hpp b/include/mbgl/map/map_observer.hpp
index 98b218f8f0..8ad9e93d0b 100644
--- a/include/mbgl/map/map_observer.hpp
+++ b/include/mbgl/map/map_observer.hpp
@@ -3,11 +3,17 @@
 #include <mbgl/style/source.hpp>
 
 #include <cstdint>
-#include <exception>
 #include <string>
 
 namespace mbgl {
 
+enum class MapLoadError {
+    StyleParseError,
+    StyleLoadError,
+    NotFoundError,
+    UnknownError,
+};
+
 class MapObserver {
 public:
     virtual ~MapObserver() = default;
@@ -32,7 +38,7 @@ public:
     virtual void onCameraDidChange(CameraChangeMode) {}
     virtual void onWillStartLoadingMap() {}
     virtual void onDidFinishLoadingMap() {}
-    virtual void onDidFailLoadingMap(std::exception_ptr) {}
+    virtual void onDidFailLoadingMap(MapLoadError, const std::string&) {}
     virtual void onWillStartRenderingFrame() {}
     virtual void onDidFinishRenderingFrame(RenderMode) {}
     virtual void onWillStartRenderingMap() {}