Email obfuscation breaks production builds

[pugson]

$ NODE_ENV=production node ./tools/image-optimizer.js && node ./tools/webp-converter.js && parcel build ./src/*.html --no-source-maps --public-url ./
🚨  /Users/pugson/Sites/thinko-animation-studio-web/src/about.html: tree.forEach is not a function
    at collapseWhitespace (/Users/pugson/Sites/thinko-animation-studio-web/node_modules/htmlnano/lib/modules/collapseWhitespace.js:24:10)
    at /Users/pugson/Sites/thinko-animation-studio-web/node_modules/htmlnano/lib/modules/collapseWhitespace.js:32:28
    at Array.forEach (<anonymous>)
    at collapseWhitespace (/Users/pugson/Sites/thinko-animation-studio-web/node_modules/htmlnano/lib/modules/collapseWhitespace.js:24:10)
    at /Users/pugson/Sites/thinko-animation-studio-web/node_modules/htmlnano/lib/modules/collapseWhitespace.js:32:28
    at Array.forEach (<anonymous>)
    at collapseWhitespace (/Users/pugson/Sites/thinko-animation-studio-web/node_modules/htmlnano/lib/modules/collapseWhitespace.js:24:10)
    at /Users/pugson/Sites/thinko-animation-studio-web/node_modules/htmlnano/lib/modules/collapseWhitespace.js:32:28
    at Array.forEach (<anonymous>)
    at collapseWhitespace (/Users/pugson/Sites/thinko-animation-studio-web/node_modules/htmlnano/lib/modules/collapseWhitespace.js:24:10)
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.