Cannot read property 'constructor' of undefined

After I upgrade to 3.0.4 it show me the errors:

```
ERROR in ./src/index.ts
Module build failed: TypeError: Cannot read property 'constructor' of undefined
    at Object.getTypeScriptInstance (./node_modules/ts-loader/dist/instances.js:26:37)
    at Object.loader (./node_modules/ts-loader/dist/index.js:24:39)
```

Fallback to 3.0.3 works great.