Fails on node 10.4.0 - 10.6.0 with `symbol lookup error: [...] undefined symbol: napi_create_bigint_words`

[davidmurdoch]

BigInt was introduced in node 10.4.0 (which uses V8 v6.7), which is why I started testing at this version.

Test run output:

david @ ~/work/bigint-buffer (master)
└─ $ ▶ npm run test:node

> bigint-buffer@1.1.5 test:node /home/david/work/bigint-buffer
> mocha -r ts-node/register src/**/*.spec.ts --timeout 40000



  Try buffer conversion (little endian)
/home/david/.nvm/versions/node/v10.6.0/bin/node: symbol lookup error: /home/david/work/bigint-buffer/build/Release/bigint_buffer.node: undefined symbol: napi_create_bigint_words
npm ERR! file sh
npm ERR! code ELIFECYCLE
npm ERR! errno ENOENT
npm ERR! syscall spawn
npm ERR! bigint-buffer@1.1.5 test:node: `mocha -r ts-node/register src/**/*.spec.ts --timeout 40000`
npm ERR! spawn ENOENT
npm ERR! 
npm ERR! Failed at the bigint-buffer@1.1.5 test:node script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/david/.npm/_logs/2020-04-24T00_49_18_551Z-debug.log

Node versions 10.4.0, 10.4.1, 10.5.0, and 10.6.0 all fail. It does work on 10.7.0 and up.

The project's package.json "engines" section is:

"engines": {
  "node": ">= 10.0.0"
}

Would you like a PR updating the engines section to reflect the actual working node versions?