Invalid regular expression: Nothing to repeat

I'm trying to highlight some textareas in order to color in red all texts inside curly brackets:

```javascript
$('textarea').highlightTextarea({
'words': [{
'color': 'lightsalmon',
'words': ['{(.+?)}']
}]
});
```

It's working fine for most examples, except when the component tries to highlight curly bracked with only numbers inside:

```
{1104}{695}{592}{290}{278}{284}{291}
```

On highlighting, component returns the following error and aborts: "Uncaught SyntaxError: Invalid regular expression: /{1104}/: Nothing to repeat".

I also tried changing the regex to ['{[A-z0-9: ]*}'], but the problem persists.

I'm using version 3.1.3, and jQuery 1.11.0.