fix leaks caused by early exit

[todo]

RT/src/core/scene/init.c

Lines 120 to 125 in 950919a

	exit(FAILURE); // TODO: fix leaks caused by early exit
	}
	camera_init(&scene->camera, dict_get(json_root, "camera"));
	scene->obj_container.root = NULL;
	objects_init(&scene->obj_container, dict_get(json_root, "objects"));
	}

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This issue was generated by todo based on a TODO comment in 950919a when #30 was merged. cc @emiflake.