In the past couple of days, this seems to have stopped working on Node 12 (v12.22.12):

npx wait-on http://localhost:8080
npx: installed 20 in 4.549s
Unexpected token '.'

I see this package hasn't been released in that period, so presumably something has changed in one of the dependencies (direct or transitive).

I'm aware that Node 12 (LTS) is end of life (https://endoflife.date/nodejs), however the readme of this package states it's supported. This issue arose in an old CI job that was using Node 12 and npx wait-on via https://github.com/cypress-io/circleci-orb