Error thrown when trying to getType() of a unregistered type

```
(node:137) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'targetSource' of undefined
    at Function.IoCContainer.getType (/home/coolerminers/node_modules/typescript-ioc/es5.js:143:23)
    at Function.Container.getType (/home/coolerminers/node_modules/typescript-ioc/es5.js:86:29)
```