bsconfig.json

{
    "name": "hello",
    "sources": [
        {
            "dir": "src",
            "subdirs": true
        }
    ],
    "bsc-flags": ["-bs-super-errors"],
    "bs-dependencies": [
        "reason-react"
    ],
    "reason": {
        "react-jsx": 2
    },
    "package-specs": ["es6"]
}

index.re

type quillEditorT;
external quill: string => quillEditorT = "" [@@bs.module];
type foo;
external import: string => foo = "" [@@bs.module "quill"];

let inline = import "blot/inline";
let editr = quill "#editor";

[%bs.raw {|
class Foo extends inline {

    custom_update(){
        console.log("BOOOM!");
    }
};
Foo.tagName = 'strong';
|}];

out

ERROR in ./src/index.re
Module parse failed: ../reason-tryies/node_modules/bs-loader/index.js??ref--0-0!../reason-tryies/src/index.re Unexpected token (16:1)
You may need an appropriate loader to handle this file type.
|         console.log("BOOOM!");
|     }
| };
| Foo.tagName = 'strong';
| ));

package.json

{
  "name": "reason-tryies",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "build": "webpack",
    "start": "webpack-dev-server",
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "bs-loader": "^1.6.0",
    "bs-platform": "^1.9.1",
    "reason-react": "^0.2.4",
    "webpack": "^3.5.5",
    "webpack-dev-server": "^2.7.1"
  },
  "dependencies": {
    "quill": "^1.3.2"
  }
}

webpack.config.js

const path = require('path');

module.exports = {
    entry: './src/index.re',
    output: {
        filename: 'bundle.js',
        path: path.resolve(__dirname, 'dist')
    },
    devtool: 'inline-source-map',
    module: {
        rules: [
            // Set up Reason and OCaml files to use the loader
            {
                test: /\.(re|rei|ml)$/,
                use:[
                    {
                        loader: 'bs-loader',
                        options: {module: 'es6'}
                    }
                ]
            },
        ]
    },
    resolve: {
        // Add .re and .ml to the list of extensions webpack recognizes
        extensions: ['.re', '.rei', '.ml', '.js']
    },
    devServer: {
        contentBase: './dist'
    }
};