BadImageFormatException when running generate-load-scripts

Description

When running paket.exe generate-load-scripts I get a failure of:

Paket failed with
-> BadImageFormatException: Format of the executable (.exe) or library (.dll) isinvalid.

I have traced the issue (by putting in printfn logging inside DependencyCache.fs - getDllsWithinPackage) to:

Reading Assembly /home/user/.nuget/packages/microsoft.testplatform.testhost/15.5.0/lib/netstandard1.5/x64/msdia140.dll

This is coming from the Microsoft.NET.Test.Sdk package. Note I am on Mono 5.4.0 (EDIT: Tested in on Windows 10 same issue happens there).

Repro steps

Please provide the steps required to reproduce the problem

1. Bring in a solution that uses the "Microsoft.NET.Test.Sdk" package.
2. Attempt to run "mono .paket/paket.exe generate-load-scripts"

Expected behavior

Load scripts are generated.

Actual behavior

Paket failed with
-> BadImageFormatException: Format of the executable (.exe) or library (.dll) isinvalid.

Known workarounds

None

Start in DependencyCache.fs at getDllsWithinPackage and reproduce with a solution using Microsoft.NET.Test.Sdk, running mono .paket/paket.exe generate-load-scripts. Trace handling of msdia140.dll at the reported package path; done means load scripts are generated without BadImageFormatException.