The 'Sting' is returned by the function GetUnicodeStringTextAndSize. If it is NULL, function GetUnicodeStringTextAndSize will return EFI_OUT_OF_RESOURCES, and error handling codes will cover it. So the pointer 'Sting' can not be NULL when using it. So we can add the ASSERT codes. Cc: Eric Dong <eric.dong@intel.com> Cc: Hao Wu <hao.a.wu@intel.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Dandan Bi <dandan.bi@intel.com> Reviewed-by: Hao Wu <hao.a.wu@intel.com>