[HotReloadAgent] Update MetadataUpdateHandlerInvoker to be nullable friendly

[maraf]

Contributes to dotnet/aspnetcore#61272

PS> dotnet build .\src\Components\WebAssembly\WebAssembly\src\Microsoft.AspNetCore.Components.WebAssembly.csproj
Restore complete (1.3s)
  Microsoft.JSInterop succeeded (0.6s) → artifacts\bin\Microsoft.JSInterop\Debug\net10.0\Microsoft.JSInterop.dll
  Microsoft.JSInterop.WebAssembly succeeded (0.6s) → artifacts\bin\Microsoft.JSInterop.WebAssembly\Debug\net10.0\Microsoft.JSInterop.WebAssembly.dll
  Microsoft.AspNetCore.Components succeeded (1.4s) → artifacts\bin\Microsoft.AspNetCore.Components\Debug\net10.0\Microsoft.AspNetCore.Components.dll
  Microsoft.AspNetCore.Components.Forms succeeded (0.9s) → artifacts\bin\Microsoft.AspNetCore.Components.Forms\Debug\net10.0\Microsoft.AspNetCore.Components.Forms.dll
  Microsoft.AspNetCore.Components.Web succeeded (0.8s) → artifacts\bin\Microsoft.AspNetCore.Components.Web\Debug\net10.0\Microsoft.AspNetCore.Components.Web.dll
  Microsoft.AspNetCore.Components.WebAssembly failed with 1 error(s) (0.7s)
    C:\Nuget\microsoft.dotnet.hotreload.agent\10.0.100-preview.5.25252.107\contentFiles\cs\netstandard2.1\MetadataUpdateHandlerInvoker.cs(334,38): error CS8600: Converting null literal or possible null value to non-nullable type.

Build failed with 1 error(s) in 5.6s

[Copilot]

Pull Request Overview

This pull request updates the MetadataUpdateHandlerInvoker to be nullable friendly, addressing the CS8600 compiler error when converting null values.

• Changed the declaration of assemblyIdentifier to allow null values.

Comments suppressed due to low confidence (1)

src/BuiltInTools/HotReloadAgent/MetadataUpdateHandlerInvoker.cs:330

• Using a nullable type for assemblyIdentifier resolves the compiler error; please ensure that all subsequent usages of assemblyIdentifier properly handle the potential null value.

string? assemblyIdentifier;