NullReferenceException from AspNetCore analyzer RegistrationExpectedInASPNetIntegration

[jviau]

Description

After some refactoring the functions host CI started failing due to this error:

##[error]CSC(0,0): Error AD0001: Analyzer 'Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore.RegistrationExpectedInASPNetIntegration' threw an exception of type 'System.NullReferenceException' with message 'Object reference not set to an instance of an object.'.

Unfortunately, there is not much more information. Not even line number. This is affecting DotNetIsolated60.csproj, but something about it is sensitive to other msbuild properties as this only began after some refactoring of mine.

Maybe this is due to the way the app if/elses calling the expected method? https://github.com/Azure/azure-functions-host/blob/dev/test/DotNetIsolated60/Program.cs#L12

Steps to reproduce

Unable to narrow down repro, this happens in functions host CI but not locally. Failing CI here