Invalid number error for Singapore number starting with `+6589xxxxxx` and `+6580xxxxxx`

[kingcashthefifth]

Hi @mattbornski ,
I have encountered an invalid number error while trying to do the following:

var libphonenumber = require('libphonenumber');

const testNum1 = '+6581002500';
const testNum2 = '+6582002500';
const testNum3 = '+6589002500';
const testNum4 = '+6580002500';

console.log('libphonenumber, testNum1: ', libphonenumber.validate(testNum1));
console.log('libphonenumber, testNum2: ', libphonenumber.validate(testNum2));
console.log('libphonenumber, testNum3 ', libphonenumber.validate(testNum3));
console.log('libphonenumber, testNum4: ', libphonenumber.validate(testNum4));

While using variables testNum3 and testNum4 to test, there was an error as follow:

Error: Invalid number
    at validateNumber (/home/runner/DenseDirectMiddleware/node_modules/libphonenumber/lib/index.js:53:21)
    at Object.validate (/home/runner/DenseDirectMiddleware/node_modules/libphonenumber/lib/index.js:99:23)
    at /home/runner/DenseDirectMiddleware/index.js:31:58
    at Script.runInContext (vm.js:131:20)
    at Object.<anonymous> (/run_dir/interp.js:156:20)
    at Module._compile (internal/modules/cjs/loader.js:1133:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1153:10)
    at Module.load (internal/modules/cjs/loader.js:977:32)
    at Function.Module._load (internal/modules/cjs/loader.js:877:14)

+6589xxxxxx and +6580xxxxxx are both valid singapore number formats.
Are you able to provide a fix for this?

Thank you!