world: use unit parameter to lookup CameraInstance

src/world/world.cpp

@@ -262,8 +262,10 @@ CameraInstance World::camera_create(UnitId id, const CameraDesc& cd, const Matri
 	return camera_make_instance(last);
 }
 
-void World::camera_destroy(UnitId unit, CameraInstance i)
+void World::camera_destroy(UnitId unit, CameraInstance /*ci*/)
 {
+	CameraInstance i = camera_instances(unit);
+
 	const u32 last = array::size(_camera) - 1;
 	const UnitId u = _camera[i.i].unit;
 	const UnitId last_u = _camera[last].unit;

src/world/world.h

@@ -94,7 +94,7 @@ struct World
 	CameraInstance camera_create(UnitId id, const CameraDesc& cd, const Matrix4x4& tr);
 
 	/// Destroys the camera @a id.
-	void camera_destroy(UnitId unit, CameraInstance i);
+	void camera_destroy(UnitId unit, CameraInstance ci);
 
 	/// Returns the camera owned by unit @a id.
 	CameraInstance camera_instances(UnitId id);