Throw an exception when embedded verbs file is not found.

src/Generator/Passes/GetterSetterToPropertyPass.cs

@@ -307,10 +307,8 @@ namespace CppSharp.Passes
             var assembly = Assembly.GetExecutingAssembly();
             using (var resourceStream = GetResourceStream(assembly))
             {
-                // For some reason, embedded resources are not working when compiling the
-                // Premake-generated VS project files with xbuild under OSX. Workaround this for now.
                 if (resourceStream == null)
-                    return;
+                    throw new Exception("Cannot find embedded verbs data resource.");
 
                 using (var streamReader = new StreamReader(resourceStream))
                     while (!streamReader.EndOfStream)