fix: dont overwrite global config when setting unlimited

[Uzlopak]

Another approach to fix #88

Checklist

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

[Eomm]

What we need to support more clearly due the fastify test:

• update the readme (the emitter is no more a map of boolean)
• how the user check if a code has been emitted?
• how the user set that a code has been emitted?

Could you add some info as comment?
I do bit ops once per year and I don't remember it, so reading back this code would become just stressful

[jsumners]

Please provide a test that proves it is still possible to reset the state of an error by setting its emitted "property" to false.