When revamping the build, I tried to resolve a rollup warning that had been occurring on the build for a long time:
"(!) `this` has been rewritten to `undefined`
It occurs because of typescript's Object.assign polyfill, which uses this on the global scope. If you set context: 'window' in the rollup config, it will silence the warning, but it will cause issues if CountUp is not run in the browser. Allowing rollup to rewrite this to undefined on just the global scope is harmless and doesn't break anything, so I reverted the change.