[NEW!!!] Only stop proservices if err is nil

It'd be safe today to do so, but might not be tomorrow.
The good practice is always to not touch the returned object if err is not nil.

windows-agent/internal/proservices/proservices_test.go

@@ -83,7 +83,9 @@ func TestNew(t *testing.T) {
 			}
 
 			s, err := proservices.New(ctx, publicDir, privateDir, proservices.WithRegistry(reg))
-			defer s.Stop(ctx)
+			if err == nil {
+				defer s.Stop(ctx)
+			}
 			if tc.wantErr {
 				require.Error(t, err, "New should return an error")
 				return