Build fails with Exception "Absolute path expected. (Parameter 'fullPath')"

[BloodBaz]

Describe the bug

When assessing a .NET Framework 4.8 Web Forms application and associated libraries, the assessment fails to build. Log file shows:

[2023-11-10 12:38:05 ERR] (1.9.9) PortingAssistant.Api.Application: Failed to analyze solution
{
  "RequestPayload": {
    "solutionFilePath": "C:\\path\\to\\solution\\My Solution.sln",
    "runId": "01234567-89ab-cdef-0123-456789abcdef",
    "triggerType": "UserRequest",
    "settings": {
      "IgnoreProjects": null,
      "TargetFramework": "net6.0",
      "ContiniousEnabled": false,
      "CompatibleOnly": false,
      "ActionsOnly": false,
      "UseGenerator": false,
      "VisualStudioVersion": null
    },
    "preTriggerData": {}
  },
  "RequestType": "AnalyzeSolutionRequest",
  "TraceId": "9b93d951-d93b-45f7-81d9-74ff783b2a64",
  "TimeStamp": "2023-11-10 12:37:59Z"
}
System.ArgumentException: Absolute path expected. (Parameter 'fullPath')
   at PortingAssistant.Api.Application.<SetupConnection>b__5_0(AnalyzeSolutionRequest request) in C:\codebuild\tmp\output\src4028753889\src\github.com\aws\porting-assistant-dotnet-ui\packages\csharp\PortingAssistant\PortingAssistant.Api\Application.cs:line 78
[2023-11-10 12:38:05 INF] (1.9.9) PortingAssistant.Api.Application: End OnAnalyzeSolutionRequest

Expected behavior

Assessment to complete without error

Steps to Reproduce

Steps to reproduce the behavior:

1. Create a new .NET Framework 4.8 Web Forms project.
2. Create or add reference to another .NET Framework library
3. Amend Web Forms project's .csproj file so that reference to library is a valid relative path e.g.

    <Reference Include="Azure.Identity, Version=1.8.0.0, Culture=neutral, PublicKeyToken=92742159e12e44c8, processorArchitecture=MSIL">
      <HintPath>C:\packages\Azure.Identity.1.8.0\lib\netstandard2.0\Azure.Identity.dll</HintPath>
    </Reference>

to

    <Reference Include="Azure.Identity, Version=1.8.0.0, Culture=neutral, PublicKeyToken=92742159e12e44c8, processorArchitecture=MSIL">
      <HintPath>..\..\..\..\Azure.Identity.1.8.0\lib\netstandard2.0\Azure.Identity.dll</HintPath>
    </Reference>

VS2022 will compile the project without issue but the asessment project with fail with the above error.

Desktop

• OS: Windows 11