hw/uefi: fix error handling in uefi_vars_json_save

Catch lseek errors.  Return on errors.
Use autoptr for the GString to simplify cleanup.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-ID: <20250319141159.1461621-3-kraxel@redhat.com>
1 file changed