Fix null reference bugs and unsafe code patterns across codebase

[Copilot]

Systematic fix of null reference hazards, unsafe null-forgiving operators, and missing validation across the codebase.

Core Library

• RefitterCodeGenerator.cs: GetOutputFilePath returned invalid path "\Output.cs" when workingDirectory was null
• StringExtensions.cs: GetDescription<T> accessed memInfo[0] without bounds check
• CSharpFileMerger.cs: Directory.GetParent() can return null; removed unsafe ! operators
• PathProvider.cs: programFiles.Replace() called without null guard after GetFolderPath which can return empty
• DependencyInstaller.cs: Kiota version mismatch had empty TODO block; now calls UpdateKiotaTool() with exception handling
• FileDownloader.cs: MoveFile silently failed; now logs warning and returns temp file as fallback
• NpmHelper.cs: string prefix = null! caused issues in callback; use empty string
• KiotaCodeGenerator.cs, OpenApiCSharpCodeGenerator.cs, NSwagStudioCodeGenerator.cs: Multiple unsafe Path.GetDirectoryName()! patterns replaced with proper fallbacks

CLI

• JMeterCommand.cs: Unsafe Path.GetDirectoryName()! on user input
• OpenApiGeneratorCommand.cs: Missing null check for factory parameter (inconsistent with other params)

VSCode Extension

• version-utils.ts: Number() produces NaN for invalid version parts; use parseInt with fallback to 0

// Before
var workingDirectory = Path.GetDirectoryName(inputFile);
processLauncher.Start(command, arguments, Path.GetDirectoryName(nswagStudioFile)!);

// After  
var workingDirectory = Path.GetDirectoryName(inputFile) ?? Directory.GetCurrentDirectory();
processLauncher.Start(command, arguments, workingDirectory);

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:

• azuresdkartifacts.blob.core.windows.net
  • Triggering command: /usr/bin/dotnet dotnet restore --no-dependencies /home/REDACTED/work/apiclientcodegen/apiclientcodegen/test/GeneratedCode/GeneratedCode.slnx --packages /home/REDACTED/work/apiclientcodegen/.codeql-scratch/dbs/csharp/working/packages /p:DisableImplicitNuGetFallbackFolder=true --verbosity normal /p:TargetFrameworkRootPath=/home/REDACTED/work/apiclientcodegen/.codeql-scratch/dbs/csharp/working/emptyFakeDotnetRoot /p:NetCoreTargetingPackRoot=/home/REDACTED/work/apiclientcodegen/.codeql-scratch/dbs/csharp/working/emptyFakeDotnetRoot /p:AllowMissingPrunePackageData=true (dns block)
  • Triggering command: /usr/bin/dotnet dotnet restore --no-dependencies /home/REDACTED/work/apiclientcodegen/apiclientcodegen/test/GeneratedCode/AutoRest-V3/Net462/Net462.csproj --packages /home/REDACTED/work/apiclientcodegen/.codeql-scratch/dbs/csharp/working/packages /p:DisableImplicitNuGetFallbackFolder=true --verbosity normal /p:TargetFrameworkRootPath=/home/REDACTED/work/apiclientcodegen/.codeql-scratch/dbs/csharp/working/emptyFakeDotnetRoot /p:NetCoreTargetingPackRoot=/home/REDACTED/work/apiclientcodegen/.codeql-scratch/dbs/csharp/working/emptyFakeDotnetRoot /p:AllowMissingPrunePackageData=true (dns block)
  • Triggering command: /usr/bin/dotnet dotnet restore --no-dependencies /home/REDACTED/work/apiclientcodegen/apiclientcodegen/test/GeneratedCode/AutoRest-V3/Net6/Net6.csproj --packages /home/REDACTED/work/apiclientcodegen/.codeql-scratch/dbs/csharp/working/packages /p:DisableImplicitNuGetFallbackFolder=true --verbosity normal /p:TargetFrameworkRootPath=/home/REDACTED/work/apiclientcodegen/.codeql-scratch/dbs/csharp/working/emptyFakeDotnetRoot /p:NetCoreTargetingPackRoot=/home/REDACTED/work/apiclientcodegen/.codeql-scratch/dbs/csharp/working/emptyFakeDotnetRoot /p:AllowMissingPrunePackageData=true (dns block)
• petstore.swagger.io
  • Triggering command: /usr/share/dotnet/dotnet /usr/share/dotnet/dotnet exec --runtimeconfig /home/REDACTED/work/apiclientcodegen/apiclientcodegen/src/Core/ApiClientCodeGen.Core.Tests/bin/Debug/net8.0/ApiClientCodeGen.Core.Tests.runtimeconfig.json --depsfile /home/REDACTED/work/apiclientcodegen/apiclientcodegen/src/Core/ApiClientCodeGen.Core.Tests/bin/Debug/net8.0/ApiClientCodeGen.Core.Tests.deps.json /home/REDACTED/work/apiclientcodegen/apiclientcodegen/src/Core/ApiClientCodeGen.Core.Tests/bin/Debug/net8.0/testhost.dll --port 39809 --endpoint 127.0.0.1:039809 --role client --parentprocessid 4139 --telemetryoptedin false (dns block)
  • Triggering command: /usr/share/dotnet/dotnet /usr/share/dotnet/dotnet exec --runtimeconfig /home/REDACTED/work/apiclientcodegen/apiclientcodegen/src/Core/ApiClientCodeGen.Core.Tests/bin/Debug/net8.0/ApiClientCodeGen.Core.Tests.runtimeconfig.json --depsfile /home/REDACTED/work/apiclientcodegen/apiclientcodegen/src/Core/ApiClientCodeGen.Core.Tests/bin/Debug/net8.0/ApiClientCodeGen.Core.Tests.deps.json /home/REDACTED/work/apiclientcodegen/apiclientcodegen/src/Core/ApiClientCodeGen.Core.Tests/bin/Debug/net8.0/testhost.dll --port 40715 --endpoint 127.0.0.1:040715 --role client --parentprocessid 4266 --telemetryoptedin false (dns block)
  • Triggering command: /usr/share/dotnet/dotnet /usr/share/dotnet/dotnet exec --runtimeconfig /home/REDACTED/work/apiclientcodegen/apiclientcodegen/src/Core/ApiClientCodeGen.Core.Tests/bin/Debug/net8.0/ApiClientCodeGen.Core.Tests.runtimeconfig.json --depsfile /home/REDACTED/work/apiclientcodegen/apiclientcodegen/src/Core/ApiClientCodeGen.Core.Tests/bin/Debug/net8.0/ApiClientCodeGen.Core.Tests.deps.json /home/REDACTED/work/apiclientcodegen/apiclientcodegen/src/Core/ApiClientCodeGen.Core.Tests/bin/Debug/net8.0/testhost.dll --port 44921 --endpoint 127.0.0.1:044921 --role client --parentprocessid 5512 --telemetryoptedin false (dns block)
• westeurope-5.in.applicationinsights.azure.com
  • Triggering command: /home/REDACTED/work/apiclientcodegen/apiclientcodegen/src/CLI/ApiClientCodeGen.CLI/bin/Debug/net8.0/rapicgen /home/REDACTED/work/apiclientcodegen/apiclientcodegen/src/CLI/ApiClientCodeGen.CLI/bin/Debug/net8.0/rapicgen csharp nswag Swagger.json GeneratedCode /tmp/test-output.cs (dns block)
  • Triggering command: /home/REDACTED/work/apiclientcodegen/apiclientcodegen/src/CLI/ApiClientCodeGen.CLI/bin/Debug/net8.0/rapicgen /home/REDACTED/work/apiclientcodegen/apiclientcodegen/src/CLI/ApiClientCodeGen.CLI/bin/Debug/net8.0/rapicgen csharp nswag Swagger.json GeneratedCode /tmp/test-output2.cs 076534-d89btt.tx-d p/bin/git (dns block)
  • Triggering command: /home/REDACTED/work/apiclientcodegen/apiclientcodegen/src/CLI/ApiClientCodeGen.CLI/bin/Debug/net8.0/rapicgen /home/REDACTED/work/apiclientcodegen/apiclientcodegen/src/CLI/ApiClientCodeGen.CLI/bin/Debug/net8.0/rapicgen csharp nswag Swagger.json GeneratedCode /tmp/final-test.cs credential.username bash (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

Find and fix bugs and issues in this repository. Be as thorough as possible

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