Fix build failure detection [skip ci]

Author: nblumhardt

Build.ps1

@@ -29,7 +29,7 @@ foreach ($src in ls src/*) {
     } else {
         & dotnet pack -c Release -o ..\..\artifacts --no-build
     }
-    if($LASTEXITCODE -ne 0) { exit 1 }    
+    if($LASTEXITCODE -ne 0) { throw "build failed" }    
 
     Pop-Location
 }
@@ -40,7 +40,7 @@ foreach ($test in ls test/*.Tests) {
 	echo "build: Testing project in $test"
 
     & dotnet test -c Release
-    if($LASTEXITCODE -ne 0) { exit 3 }
+    if($LASTEXITCODE -ne 0) { throw "tests failed" }    
 
     Pop-Location
 }