This will never be true.  `computeIcrfToFixedMatrix` returns undefined, but it doesn't set transformMatrix to undefined (it couldn't if it wanted to, because Javascript doesn't support passing references by reference).

The easiest fix is to replace this if with:

```javascript
if (typeof Transforms.computeIcrfToFixedMatrix(frameState.time, transformMatrix) === 'undefined') {
```

And eliminate the (now redundant) call to `computeIcrfToFixedMatrix` above the if.