Exception thrown when sign strong name for Fido2.Models version = 2.0.2.0

[NJGehe]

I try to sign strong name for Fido2.Models.dll like below:

E:\Git-Repos\dashboard\Src>cd E:\Git-Repos\dashboard\Src\packages\Fido2.Models.2.0.2\lib\netstandard2.0
E:\Git-Repos\dashboard\Src\packages\Fido2.Models.2.0.2\lib\netstandard2.0>ildasm Fido2.Models.dll /out:Fido2.Models.il
E:\Git-Repos\dashboard\Src\packages\Fido2.Models.2.0.2\lib\netstandard2.0>move Fido2.Models.dll Fido2.Models.dll.unsigned
E:\Git-Repos\dashboard\Src\packages\Fido2.Models.2.0.2\lib\netstandard2.0>ilasm Fido2.Models.il /dll /resource=Fido2.Models.res /key=Fido2.Models.snk

But Error returned in last step:

Microsoft (R) .NET Framework IL Assembler.  Version 4.8.3752.0
Copyright (c) Microsoft Corporation.  All rights reserved.
Assembling 'Fido2.Models.il'  to DLL --> 'Fido2.Models.dll'
Source file is ANSI
 
Fido2.Models.il(68) : warning : Reference to undeclared extern assembly 'mscorlib'. Attempting autodetect
Fido2.Models.il(85) : error : syntax error at token '-' in:     IL_0001:  ldc.r8     -nan(ind)
 
***** FAILURE *****

Could you help give any insight why it happened?
Thanks!