Uglifier issue: Extra configuration is required for Uglifier 3.x to support ES6 in production mode (it is supported in development mode)

[improvethings]

Environment

Using minimal-mistakes-jekyll 4.21.0

• Minimal Mistakes version: 4.21.0
• Ruby gem or remote theme version: 2.7.6.2
• Jekyll version: 3.8.7
• uglifier 4.2.0
• Operating system: Debian 10 (Buster) on Linux 5.4.0-0.bpo.4-amd64 x86_64

Publishing website to Vercel from github.

Expected behavior

Expecting JEKYLL_ENV=production bundle exec jekyll serve to work.

Steps to reproduce the behavior

$ JEKYLL_ENV=production bundle exec jekyll serve
...
Incremental build: disabled. Enable with --incremental
Generating...
Jekyll Feed: Generating feed for posts
jekyll 3.8.7 | Error: Unexpected token: keyword (const). To use ES6 syntax, harmony mode must be enabled with Uglifier.new(:harmony => true).

=> const fs = require("fs");
2 const pkg = require("./package.json");
3 const filename = "assets/js/main.min.js";
4 const script = fs.readFileSync(filename);
5 const padStart = str => ("0" + str).slice(-2);
6 const dateObj = new Date();
7 const date = ${dateObj.getFullYear()}-${padStart( 8 dateObj.getMonth() + 1 9 )}-${padStart(dateObj.getDate())};

It seems to be related to this issue.

Other

Should I add jekyll-assets to the Gemfile and then the following to _config.yml:
assets:
external:
uglifier:
harmony: true

[mmistakes]

Sounds like a question for jekyll-assets. You shouldn't have to mess with any of the theme's assets (JavaScript or CSS) as they are already minified/uglified/and bundled in the theme.

[improvethings]

Sounds like a question for jekyll-assets. You shouldn't have to mess with any of the theme's assets (JavaScript or CSS) as they are already minified/uglified/and bundled in the theme.

I've posted it there, thanks! It looks like no one has responded to an issue there since April :(

[improvethings]

Sorry for my ignorance, but as I've not heard back from jekyll-assets in several days, what is the fastest path to get comments working on my blog in the interim if I assume I won't hear from them for months?

[mmistakes]

Not sure. This theme doesn’t use Jekyll-assets so I can’t really help as it appears to be an upstream issue with that gem.

[mmistakes]

Closing as this isn’t related to the theme. Looks like an upstream issue with a plug-in you installed.

https://github.com/digitalsparky/jekyll-minifier