TypeError: [[rawConfiguration.extends],[reportedConfiguration.extends]].flat is not a function

[bagage]

🐛 Bug Report

• tslint-to-eslint-config version: 0.2.11
• TSLint version: 5.18.0
• ESLint version: none?
• Node version: 10.17.0

Actual Behavior

1. I generated an empty angular project with ng new, ng 8.1.3.
2. I updated manually tslint from 5.15 to 5.18 since this is the minimum required version
3. Then I ran npx tslint-to-eslint-config and expected it to migrate from tslint to eslint

But I got this error:

npx: installed 41 in 3.972s
❌ 1 error running tslint-to-eslint: ❌
TypeError: [[rawConfiguration.extends],[reportedConfiguration.extends]].flat is not a function
    at exports.findTSLintConfiguration (/home/user/.npm/_npx/19151/lib/node_modules/tslint-to-eslint-config/src/input/findTSLintConfiguration.js:22:10)
    at process._tickCallback (internal/process/next_tick.js:68:7)

Expected Behavior

I'd expected it to migrate to eslint smoothly.

Reproduction

tslint-to-eslint-config is empty.

[humodz]

Same issue, using node 10.16.0
A temporary workaround is adding the following lines to node_modules/tslint-to-eslint-config/bin/tslint-to-eslint-config, before the require:

if (!Array.prototype.flat) {
    Object.defineProperty(Array.prototype, 'flat', {
        configurable: true,
        value: function flat () {
            var depth = isNaN(arguments[0]) ? 1 : Number(arguments[0]);

            return depth ? Array.prototype.reduce.call(this, function (acc, cur) {
                if (Array.isArray(cur)) {
                    acc.push.apply(acc, flat.call(cur, depth - 1));
                } else {
                    acc.push(cur);
                }

                return acc;
            }, []) : Array.prototype.slice.call(this);
        },
        writable: true
    });
}

if (!Object.prototype.fromEntries) {
    Object.defineProperty(Object.prototype, 'fromEntries', {
        configurable: true,
        writable: true,
        value: function fromEntries (iterable) {
            return [...iterable].reduce((obj, [key, val]) => {
                obj[key] = val
                return obj
            }, {})
        }
    })
}

[jeremyyap]

This should be the same issue as #260, only Node 12+ is supported as stated here.

[JoshuaKGoldberg]

Mmhh, if this is a common complaint then the package should support Node 10. I'll fix.

Thanks for reporting & discussing, folks!