simply remove unused dependencies fixes this issue, but I removed
all package-lock.json / yarn.lock since the demo should always be
in sync with the codebase
BREAKING CHANGE: ship to Node.js 8, the dist/liquid.cjs.js (main) nolonger
supports Node.js 6, other bundles are also provided via dist/liquid.esm.js, dist/liquid.js (ES5 umd) and liquid.min.js (minified ES5 umd)