Fix NullReferenceException in LocalizationModelDeserializer for malformed keys

[Copilot]

Malformed localization keys cause NullReferenceException in LoadPostActionModels and LoadManualInstructionModels. Keys like "postActions/" or "postActions/pa0/manualInstructions//text" result in null/empty values after splitting that are assigned to non-nullable string variables.

Changes

• Added null/empty checks in LoadPostActionModels and LoadManualInstructionModels before using grouped keys
• Mirrors existing defensive pattern in LoadSymbolModels and LoadChoiceModels
• Added test coverage for malformed keys in all three key types (postActions, manualInstructions, symbols)

foreach (var postActionParts in strings.GroupBy(p => p.NameParts.FirstOrDefault()))
{
    if (string.IsNullOrEmpty(postActionParts.Key))
    {
        // Post action with no ID. Ignore.
        continue;
    }
    
    string postActionId = postActionParts.Key;
    // ... continue processing
}

Malformed keys are now silently skipped instead of throwing exceptions.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• c50vsblobprodcus330.vsblob.vsassets.io
  • Triggering command: ./.dotnet/dotnet build src/Microsoft.TemplateEngine.Orchestrator.RunnableProjects/Microsoft.TemplateEngine.Orchestrator.RunnableProjects.csproj (dns block)
  • Triggering command: ./.dotnet/dotnet restore src/Microsoft.TemplateEngine.Orchestrator.RunnableProjects/Microsoft.TemplateEngine.Orchestrator.RunnableProjects.csproj --force --force-evaluate (dns block)
  • Triggering command: /home/REDACTED/work/templating/templating/.dotnet/dotnet msbuild /m /nologo /clp:Summary /v:minimal /nr:true /warnaserror /p:TreatWarningsAsErrors=true /p:ContinuousIntegrationBuild=false /home/REDACTED/work/templating/templating/artifacts/toolset/restore.proj /t:__WriteToolsetLocation /clp:ErrorsOnly;NoSummary /p:__ToolsetLocationOutputFile=/home/REDACTED/work/templating/templating/artifacts/toolset/11.0.0-beta.25527.104.txt (dns block)
• securitytools.pkgs.visualstudio.com
  • Triggering command: /opt/hostedtoolcache/CodeQL/2.23.1/x64/codeql/csharp/tools/linux64/Semmle.Autobuild.CSharp (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

System.NullReferenceException: Object reference not set to an instance of an object.
at Microsoft.TemplateEngine.Orchestrator.RunnableProjects.LocalizationModelDeserializer.<>c.b__4_4(ValueTuple`2 s)

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[marcpopMSFT]

Original report: https://developercommunity.visualstudio.com/t/NullReferenceException-in-LoadPostAction/10971178
@Evangelink does updating your post action help solve it on your side?
@baronfel is ignoring an empty postaction key the behavior you'd want? You know the template engine better than I.

[Evangelink]

Sorry it's too long ago I don't really recall. I know that after my fixes things were working for my tests in SDK but we had to revert because post actions were not supported in VS and leading to template crashing.

[baronfel]

At run-time I'm happy with this. I think the template engine has an authoring-focused NuGet Package that provides helpers - it would be awesome if at build-time these keys could be validated in some way.

[marcpopMSFT]

I didn't do any validation of this change as I'm not as familiar with this repo. I just scanned the code for where it was making the change and it's description of the change which seemed to be no longer failing at runtime with an empty postaction but rather just skipping it.