Instead of comparing to `null`, use `if(!defined(degrees))`, also, we have a new pragma system which removes these checks in a release build so this block should look like the below.
```
//>>includeStart('debug', pragmas.debug);
if(!defined(degrees)){
    throw new DeveloperError('degrees is required.');
}
//>>includeEnd('debug');
```

Notice I also changes the message to `degrees is required.`, we use the same message everywhere.

Obviously this goes for the rest of your changes too, let me know when you're done and I'll take another look.  Thanks again.