Fix 604

[mcollina]

Fixes #604

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct

[ivan-tymoshenko]

lgtm

[ivan-tymoshenko]

@Uzlopak I will approve it because I'm not sure if it makes any perf difference with i === Infinity || i === -Infinity, but if it does, feel free to open a new PR.

[Uzlopak]

It would have been this:

asNumber (i) {
    const num = i
    if (typeof i !== 'number') {
      i = Number(i)
    }
    // NaN !== NaN
    if (i !== i) { // eslint-disable-line no-self-compare
      throw new Error(`The value "${num}" cannot be converted to a number.`)
    }
    if (i === Infinity || i === -Infinity) {
      return 'null'
    }
    return '' + i
  }