Unable to strip comments from sourcemaps

I would like to export sourcemaps but strip out all comments.

 I have the following in my tsconfig (this is loaded via ts-loader)

```js
    "removeComments": true,
    "sourceMap": true,
```
My webconfig
```js
 devtool: ''source-map"
```
However all my comments are there, plain for all to see. 

The sourcemaps export fine. 

How do I remove the comments from these sourcemaps?
