```js
var message = `Failed to load '${codeUnit.url}'.\n` +
   codeUnit.nameTrace() + this.loaderHooks.nameTrace(codeUnit);
```

or

```js
var message = `Failed to load '${codeUnit.url}'.\n${
   codeUnit.nameTrace()}${this.loaderHooks.nameTrace(codeUnit)}`;
```