isoToCountryCode function will return JS error in case it can't find country related to isoCode

[jamilalisgandarov]

Please check all that apply

• [ ] visual bug
• [X] functional bug
• [ ] able to consistently reproduce

Expected Behavior

JS error shouldn't break whole application, can return undefined instead of breaking app

Current Behavior

Breaking app in case there is not country related to passed country code

Possible Solution

Issue is here: https://github.com/Yummygum/flagpack-core/blob/55fb55406047321c611b1e8a9738775175b24ee7/index.js#L10 Would be better to check if country has found before trying to get [keyToGet]

Steps to Reproduce

Pass unrelated code or GB for UK

Screenshots

Context

I am using flagpack-react to render flags based on country code passed by our end. Looks like we have mismatch for some country alpha 2 codes, but instead of breaking applicaiton, it would be better to return null from the Flag component

Your Environment

• Version used: react-flagpack: ^0.1.1
• Browser Name and version: Chrome
• Operating System and version (desktop or mobile): MacOS