Is it ever possible for this function to return an empty string, or a string not representing a GUID?
In the case of `SPDRP_BASE_CONTAINERID`, if a device driver responds to an `IRP_MN_QUERY_ID` IRP for the container ID with an invalid GUID string, we seem to store the returned string in the registry without verification (in ntoskrnl.exe/pnp.c/enumerate_new_device). It's probably worth it to at least log an error if we are not able to parse it. Thanks.