build fails: this language feature is only supported in es6 mode

[maiermic]

I tried to build for development by running npm run dist, but I get multiple errors

> npm run dist-dev && java -jar node_modules/google-closure-compiler/compiler.jar --warning_level QUIET --compilation_level SIMPLE_OPTIMIZATIONS --js dist/jschardet.js > dist/jschardet.min.js


> [email protected] dist-dev /Users/maiermic/Repositories/github/aadsm/jschardet
> mkdir -p dist && browserify index.js -s jschardet --detect-globals false -o dist/jschardet.js

dist/jschardet.js:1680: ERROR - this language feature is only supported in es6 mode: for-of loop. Use --language_in=ECMASCRIPT6 or ECMASCRIPT6_STRICT to enable ES6 features.
        for (const codingSM of self._mCodingSM) {
        ^

dist/jschardet.js:1680: ERROR - this language feature is only supported in es6 mode: const declarations. Use --language_in=ECMASCRIPT6 or ECMASCRIPT6_STRICT to enable ES6 features.
        for (const codingSM of self._mCodingSM) {
             ^

dist/jschardet.js:6722: ERROR - this language feature is only supported in es6 mode: const declarations. Use --language_in=ECMASCRIPT6 or ECMASCRIPT6_STRICT to enable ES6 features.
    const supportedCharsetNames = (function() {
    ^

dist/jschardet.js:6723: ERROR - this language feature is only supported in es6 mode: const declarations. Use --language_in=ECMASCRIPT6 or ECMASCRIPT6_STRICT to enable ES6 features.
        const charsetNames = [];
        ^

dist/jschardet.js:6724: ERROR - this language feature is only supported in es6 mode: for-of loop. Use --language_in=ECMASCRIPT6 or ECMASCRIPT6_STRICT to enable ES6 features.
        for (const prober of this._mProbers) {
        ^

dist/jschardet.js:6724: ERROR - this language feature is only supported in es6 mode: const declarations. Use --language_in=ECMASCRIPT6 or ECMASCRIPT6_STRICT to enable ES6 features.
        for (const prober of this._mProbers) {
             ^

dist/jschardet.js:7360: ERROR - this language feature is only supported in es6 mode: for-of loop. Use --language_in=ECMASCRIPT6 or ECMASCRIPT6_STRICT to enable ES6 features.
        for (const prober of self._mProbers) {
        ^

dist/jschardet.js:7360: ERROR - this language feature is only supported in es6 mode: const declarations. Use --language_in=ECMASCRIPT6 or ECMASCRIPT6_STRICT to enable ES6 features.
        for (const prober of self._mProbers) {
             ^

dist/jschardet.js:7525: ERROR - this language feature is only supported in es6 mode: const declarations. Use --language_in=ECMASCRIPT6 or ECMASCRIPT6_STRICT to enable ES6 features.
const supportedEncodings = (function() {
^

dist/jschardet.js:7526: ERROR - this language feature is only supported in es6 mode: const declarations. Use --language_in=ECMASCRIPT6 or ECMASCRIPT6_STRICT to enable ES6 features.
    const BOM_UTF = [
    ^

dist/jschardet.js:7530: ERROR - this language feature is only supported in es6 mode: const declarations. Use --language_in=ECMASCRIPT6 or ECMASCRIPT6_STRICT to enable ES6 features.
    const probers = [
    ^

dist/jschardet.js:7536: ERROR - this language feature is only supported in es6 mode: const declarations. Use --language_in=ECMASCRIPT6 or ECMASCRIPT6_STRICT to enable ES6 features.
    const encodings = BOM_UTF.slice(0);
    ^

dist/jschardet.js:7537: ERROR - this language feature is only supported in es6 mode: for-of loop. Use --language_in=ECMASCRIPT6 or ECMASCRIPT6_STRICT to enable ES6 features.
    for (const prober of probers) {
    ^

dist/jschardet.js:7537: ERROR - this language feature is only supported in es6 mode: const declarations. Use --language_in=ECMASCRIPT6 or ECMASCRIPT6_STRICT to enable ES6 features.
    for (const prober of probers) {
         ^

dist/jschardet.js:7543: ERROR - this language feature is only supported in es6 mode: const declarations. Use --language_in=ECMASCRIPT6 or ECMASCRIPT6_STRICT to enable ES6 features.
const supportedEncodingsDenormalized = (function() {
^

dist/jschardet.js:7545: ERROR - this language feature is only supported in es6 mode: for-of loop. Use --language_in=ECMASCRIPT6 or ECMASCRIPT6_STRICT to enable ES6 features.
    for (const encoding of supportedEncodings) {
    ^

dist/jschardet.js:7545: ERROR - this language feature is only supported in es6 mode: const declarations. Use --language_in=ECMASCRIPT6 or ECMASCRIPT6_STRICT to enable ES6 features.
    for (const encoding of supportedEncodings) {
         ^

dist/jschardet.js:7559: ERROR - this language feature is only supported in es6 mode: for-of loop. Use --language_in=ECMASCRIPT6 or ECMASCRIPT6_STRICT to enable ES6 features.
        for (const encoding of options.detectEncodings) {
        ^

dist/jschardet.js:7559: ERROR - this language feature is only supported in es6 mode: const declarations. Use --language_in=ECMASCRIPT6 or ECMASCRIPT6_STRICT to enable ES6 features.
        for (const encoding of options.detectEncodings) {
             ^

dist/jschardet.js:7561: ERROR - this language feature is only supported in es6 mode: template literals. Use --language_in=ECMASCRIPT6 or ECMASCRIPT6_STRICT to enable ES6 features.
                throw new Error(`Encoding ${encoding} is not supported. Supported encodings: ${supportedEncodings}.`);
                                ^

20 error(s), 0 warning(s)