🔨Fix build scripts to handle missing Visual Studio (#1626)

- Fix init.ps1 to check if Visual Studio exists before using vswhere
- Add proper null checks for MSBuild path
- Make NanoFramework build optional when MSBuild is not available
- Show clear warning messages when Visual Studio is not installed

This allows the main build to work without Visual Studio installed,
while still supporting NanoFramework builds when VS is available.

Author: angularsen

Build/build-functions.psm1

@@ -8,10 +8,17 @@ $toolsDir = "$root\.tools"
 
 $nuget = "$toolsDir\NuGet.exe"
 $vswhere = "${env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe"
-$msbuildPath = & $vswhere -latest -products * -requires Microsoft.Component.MSBuild -property installationPath
 
-if ($msbuildPath) {
-  $msbuildx64 = join-path $msbuildPath 'MSBuild\Current\Bin\amd64\MSBuild.exe'
+# Check if Visual Studio is installed before trying to find MSBuild
+if (Test-Path $vswhere) {
+  $msbuildPath = & $vswhere -latest -products * -requires Microsoft.Component.MSBuild -property installationPath 2>$null
+
+  if ($msbuildPath) {
+    $msbuildx64 = join-path $msbuildPath 'MSBuild\Current\Bin\amd64\MSBuild.exe'
+  }
+} else {
+  $msbuildPath = $null
+  $msbuildx64 = $null
 }
 
 import-module $PSScriptRoot\build-pack-nano-nugets.psm1
@@ -45,15 +52,22 @@ function Start-Build([boolean] $IncludeNanoFramework = $false) {
   }
   else
   {
-    write-host -foreground green "Build .NET nanoFramework."
-    $fileLoggerArg = "/logger:FileLogger,Microsoft.Build;logfile=$logsDir\UnitsNet.NanoFramework.msbuild.log"
-
-    # msbuild does not auto-restore nugets for this project type
-    & "$nuget" restore "$root\UnitsNet.NanoFramework\GeneratedCode\UnitsNet.nanoFramework.sln"
-
-    # now build
-    & "$msbuildx64" "$root\UnitsNet.NanoFramework\GeneratedCode\UnitsNet.nanoFramework.sln" /verbosity:minimal /p:Configuration=Release /p:Platform="Any CPU" /p:ContinuousIntegrationBuild=true $fileLoggerArg
-    if ($lastexitcode -ne 0) { exit 1 }
+    # Check if MSBuild is available before attempting NanoFramework build
+    if (-not $msbuildx64 -or -not (Test-Path $msbuildx64)) {
+      write-host -foreground yellow "Cannot build .NET nanoFramework - MSBuild not found. Install Visual Studio to build NanoFramework projects."
+      write-host -foreground yellow "Continuing with main build only..."
+    }
+    else {
+      write-host -foreground green "Build .NET nanoFramework."
+      $fileLoggerArg = "/logger:FileLogger,Microsoft.Build;logfile=$logsDir\UnitsNet.NanoFramework.msbuild.log"
+
+      # msbuild does not auto-restore nugets for this project type
+      & "$nuget" restore "$root\UnitsNet.NanoFramework\GeneratedCode\UnitsNet.nanoFramework.sln"
+
+      # now build
+      & "$msbuildx64" "$root\UnitsNet.NanoFramework\GeneratedCode\UnitsNet.nanoFramework.sln" /verbosity:minimal /p:Configuration=Release /p:Platform="Any CPU" /p:ContinuousIntegrationBuild=true $fileLoggerArg
+      if ($lastexitcode -ne 0) { exit 1 }
+    }
   }
 
   write-host -foreground blue "Start-Build...END`n"

Build/init.ps1

@@ -27,16 +27,31 @@ if (-not (Test-Path "$nugetPath")) {
 ###################################################
 ## TODO: OK to remove after moving to AZDO pipeline
 $VsWherePath = "${env:PROGRAMFILES(X86)}\Microsoft Visual Studio\Installer\vswhere.exe"
-$VsPath = $(&$VsWherePath -latest -property installationPath)
-$msbuildPath = Join-Path -Path $VsPath -ChildPath "\MSBuild"
+
+# Check if Visual Studio is installed
+if (Test-Path $VsWherePath) {
+  $VsPath = $(&$VsWherePath -latest -property installationPath 2>$null)
+  if ($VsPath) {
+    $msbuildPath = Join-Path -Path $VsPath -ChildPath "\MSBuild"
+    Write-Host -Foreground Green "Visual Studio found at: $VsPath"
+  } else {
+    Write-Host -Foreground Yellow "Visual Studio not found via vswhere, NanoFramework builds will be skipped"
+    $VsPath = $null
+    $msbuildPath = $null
+  }
+} else {
+  Write-Host -Foreground Yellow "Visual Studio not installed - NanoFramework builds will be skipped"
+  $VsPath = $null
+  $msbuildPath = $null
+}
 
 # Install dotnet CLI tools declared in /.config/dotnet-tools.json
 pushd $root
 dotnet tool restore
 popd
 
 # Install .NET nanoFramework build components
-if (!(Test-Path "$msbuildPath/nanoFramework")) {
+if ($msbuildPath -and !(Test-Path "$msbuildPath/nanoFramework")) {
   Write-Host "Installing .NET nanoFramework VS extension..."
 
   [System.Net.WebClient]$webClient = New-Object System.Net.WebClient
@@ -60,7 +75,7 @@ if (!(Test-Path "$msbuildPath/nanoFramework")) {
 
   Write-Output "VsWherePath is: $VsWherePath"
 
-  $VsInstance = $(&$VSWherePath -latest -property displayName)
+  $VsInstance = $(&$VSWherePath -latest -property displayName 2>$null)
 
   Write-Output "Latest VS is: $VsInstance"