Reproduction

import { init, parse } from 'es-module-lexer'

await init

parse('const of=1;console.log(of/1)')

StackBlitz: https://stackblitz.com/edit/stackblitz-starters-ku65d9?file=index.mjs

Although of is an identifier with a special meaning, it is not reserved:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Lexical_grammar#identifiers_with_special_meanings

This also runs fine in Node/Chrome: const of=1;console.log(of/1)